COMMISSION F: Wave Propagation
and Remote Sensing (November 2004 – October 2007)
Edited
by Yoshio Yamaguchi
Contents: F1 Wave Propagation
F1.1 Terrestrial Fixed Radio System
A.
Effect of Precipitation
B.
Effect of Vegetation
C.
Others
F1.2 Satellite Radio System
A.
Effects of Rain
B.
Effects of Other Factors
F1.3
A.
Macrocell/Microcell Systems
B.
MIMO Channel Modeling and Measurement Method
C.
Formulation of
D.
Ultra Wideband
E.
Intelligent Transportation System (ITS)
F.
Others
F2 Remote Sensing
F2.1 Atmosphere
A.
GPS meteorology
B. Various techniques of observation in troposphere with MST
radars
C.
Mesosphere and Lower Thermosphere (MLT) Region
D.
Radio Acoustic Sounding System (RASS)
E. Spaceborne Sensors
F2.2 Hydrometeors and Other Particles
A. Ground-based remote sensing studies
B. Space-based remote sensing studies
C. Others
F2.3 Ocean and Ice
F2.4 Land, Vegetation, Subsurface Objects
and Others
A. Land and Vegetation
B. Subsurface Objects and Landmine
Detection
C. Others
F1.
Wave Propagation
F1.1
Terrestrial Fixed Radio System
A.
Effect of Precipitation
The most serious transmission impairment is caused by rain
on radio links using frequencies above about 10 GHz. Demands for broadband
wireless systems have been promoting the study on rain statistics.
In the system design, it is required to
predict the rain attenuation distribution for radio link, and accordingly it is
necessary to know one-minute rain rate distribution. Using the databank made at
Kitami Institute of Technology, new different integration time rain rates
conversion method is proposed. This method uses the M distribution and regional
climatic parameters. As the results, it was found that this method is
applicable with good accuracy for any integration time and any locations in the
world [Ito and Hosoya, 2005]. On the world wide basis, however, the
observations of rain rate are made mainly with longer integration times such as
60 minutes in
An accurate Cumulative Distribution
Functions (CDF) statistics of high resolution 1-minute rainfall rate converted
from low resolution 1-minute rainfall (precipitation) data measured by Japan
Meteorological Agency using 0.5mm tipping bucket rain gauge at 136 locations is
shown by using a newly developed conversion method. Based on the statistical
analysis of obtained CDF curves, the suitable distribution function model for rain
attenuation probability prediction method which is applicable to the wide range
quality objective is studied. It is shown that M-distribution function model is
superior to Gamma, Log-normal and Conditional Log-normal distribution function
models [Ono et al., 2006a].
The distance characteristics of the
rainfall spatial correlation are analyzed based on the rainfall data of
high-resolution meteorological radar in addition to the rainfall data obtained
through the AMeDAS. The dependency of the rainfall intensity on distance is
confirmed. As a result of reflecting these study results in a typical link
budget, and the rain attenuation margin is approximately 4.6 dB less than the
one of the existing method [Akimoto and Watanabe, 2004]. As a result of the analysis
of the rainfall data measured by 11 tipping bucket rain gages and a drop
counting rain gage which are located at 11 sites around Otemachi in Tokyo, it
is given that spatial correlation characteristics as a function of distance gdh
can be approximated well by 
for gdh of shorter than about 2km, while
by 
longer than about 3km. Considering that
the specific rain attenuation is proportional to n-th (n=0.63 to 1.7) power of
rainfall rate (ITU-R Rec.P.838-3), it is shown that spatial correlation
characteristics depend greatly on the value of n, and equations to approximate
the relation between n and spatial correlation characteristics are given. A
method to integrate CDF of n-th power of point rainfall rate along a radio path
using spatial correlation characteristics of n-th power of the rainfall rate is
also given [Ono et al., 2005,2006b, 2007].
Accumulated number of events of given
duration with rain fade or rain rate exceeding specific level are investigated,
based on the experimental data of rain attenuation on 3 links at 15GHz, on 2
links at 22GHz, 1 link at 19GHz and 3 links at 32GHz, and of rain rate at 18
locations in Tokyo urban area. As the result, the relation between rain rate
duration and rain fade duration, which approximates the measured data
regardless of frequency and rain rate, is newly derived. And by using this
relation, the versatile estimating equation of the number of events with the
specific rain fade duration is obtained [Ishida et al., 2005].
A preliminary result is reported on a
terrestrial wave propagation experiment made in
B.
Effect of Vegetation
Results of experiments conducted to
examine the effect of space diversity (SD) in offsetting the attenuation
through vegetation for quasi-millimeter wave band Fixed Wireless Access (FWA) systems
are reported. The SD can improve the received signal level degradation due to
attenuation through vegetation by up to 8 - 10 dB at cumulative probability of
1% comparing to single receiver [Takahashi et al., 2004, 2005, 2006].
C.
Others
A statistical path loss model for
broadband fixed wireless access service using the S band or C band is reported.
The model is extended from the COST-231 Hata model in terms of the applicable
frequency and the correction factor for the subscriber antenna height. The
extensions were derived from the measured path loss data at 2.2 and 5.2 GHz in
rural areas. The path loss model is applicable to base-to-subscriber distances
of less than 20 km for suburban and quasi-open areas [Akimoto et al., 2006].
The distribution of the desired (direct)
to undesired (reflected) wave ratio (D/U) for quasi-millimeter wave band fixed
wireless access (FWA) systems and the technique to suppress undesired reflected
waves were studied. The D/U was measured and simulated, and the ability of the
passive beam forming (BF) technique to suppress undesired reflections was
confirmed by simulations and measurements [Takahashi and Ohmoto, 2007].
F1.2
Satellite Radio System
A.
Effects of Rain
The rain attenuation characteristics of Ku-band
satellite communications link are obtained at Equatorial Atmosphere Radar
Observatory (EAR; 0.2‹S, 100.3‹E) in Indonesia for the past four years of
2003-2006, using Japanfs domestic communication satellite Superbird C (144‹E in
orbit). The results are compared with simultaneous X-band radar observations of
convective precipitating clouds at EAR. The yearly and worst month time
percentages of both up- (14GHz) and down-link (12GHz) attenuation observed at
EAR are, as a whole, in good agreement with the ITU-R predictions. In the
attenuation range of larger than 10dB, however, the time percentages become
much smaller than the ITU-R predictions, indicating remarkable reduction of
equivalent path length down to 2 km. The X-band radar observations reveal that
this short path length is caused by fairly localized convective precipitating
clouds. Also, the intense echo cores of their typical rain cells are limited to
about 2 km along the propagation path with elevation angle of about 40‹[Maekawa
et al., 2006a]. This equivalent path length as short as 2 km is shown to be a
comparatively small value even in the tropical region compared with other
observations in nearby locations [Maekawa et al., 2006b]. The rain attenuation
is then estimated from the radar reflectivity factor (Z) of the X-band radar
obtained along the same propagation path as the satellite link, indicating the
almost same attenuation values when fairly large cloud cells have passed over
the EAR site [Tsujino et al., 2007a]. The radar observations can estimate the
attenuation with any elevation angles other than 40‹ from the RHI displays. The
estimated attenuation, however, shows no such clear dependency upon the
elevation angles of, say, 15-40‹as in the temperate region where the
attenuation tends to increases as the elevation angle decreases [Tsujino et
al., 2007b].
Directions and speeds of the motion of
rain areas are estimated for each type of rain fronts, using time differences
detected in the rain attenuation of the Ku-band satellite radio wave signals
that have been measured at Osaka Electro-Communication University (OECU) in
Neyagawa, Osaka, Research Institute of Sustainable Humanosphere (RISH) in Uji,
Kyoto, and MU Observatory (MU) of Kyoto University in Shigaraki, Shiga, for the
past five years of 2002-2006. These directions and speeds are shown to agree
well with those directly obtained from the motion of rain fronts in the weather
charts published by Japan Meteorological Agency. The rain area motion is found
to have characteristic directions according to each rain type, such as cold and
warm fronts or typhoon [Nakatani et al., 2007]. For these rain types, a
numerical estimate of the site diversity effects indicates that between two
sites among the three locations (OECU, RISH, MU) separated by 20-50km, the
joint cumulative time percentages of rain attenuation become lower as the two
sites are aligned along the directions of rain area motion. In such a case, the
distance required between the two sites may be considerably reduced compared
with the conventional ITU-R recommendations [Maekawa et al., 2007].
The Ku-band and Ka-band rain attenuation and Ka-band XPD
degradation are simultaneously measured at OECU in Neyagawa, Osaka, as well as
DSD measurements for the past three years of 2004-2006. The cross-polar phase
and frequency ratio of Ka-band to Ku-band attenuation observed at each rainfall
event agree well with their theoretical values based on the DSD detected at the
same time. Also, the Joss-drizzle type that contains comparatively smaller DSD
tends to be found in the stationary fronts of Baiu season, while the
Joss-thunderstorm type with relatively larger DSD tends to be found in evening
showers of summer season and the cold fronts of spring or autumn season [Nishio
et al., 2006].
Fading dynamics, such as fade slope, fade speed and fade
duration, in satellite links is one of the important themes for recent
broadband IP-networks. Fade slope characteristics are studied as follows.
The fade slope evaluation method using
the received signal levels from four stations located in a region of about 12
km in diameter is studied. Although some well established dependencies such as
the dependency on the rain region and on the applied filter's bandwidth have
been verified, it appears that existing fade slope model does not fit the
obtained distributions [Franklin et al., 2004]. An efficient approach to
evaluate the fade slope of the received signal level is proposed. This approach
is applied to experimental data obtained from four stations located in a region
of about 12 km in diameter in
Fade duration is also important for
analyzing the fade dynamics. Fade duration dynamics were observed in 4 close
stations. Fade duration statistics derived from collected received signal
during a critical period was analyzed. Based on the comparison of the obtained
results and the model released by the ITU-R P.1623 recommendation, some modifications
are proposed [
As a well known parameter for fade
dynamics, the level crossing rate was observed on satellite links. It was shown
that for a long run, the level crossing rate conservation law is verified and
that it depends on the sampling period for an attenuation threshold greater
than 3dB [Fondjo et al., 2006b].
The site diversity system has been proposed as a mitigating
technique for the rain attenuation on satellite links using frequencies above
about 10 GHz. A study to improve Morita-Higuti prediction method for satellite
link site diversity improvement was made by using a global databank. This
method was found to be improved by using newly derived estimation equation for
rain rate spatial correlation parameter that included regional climatic
parameters [Suzuki et al., 2005]. In site diversity systems, signals of two
earth stations located apart each other are switched. Although two prediction
methods for site diversity improvement are recommended by ITU-R, these methods
do not consider regional climatic parameters that will affect diversity
improvement. These methods may be further improved in prediction accuracy by
considering the regional climatic parameters. Modified versions of the existing
prediction methods are proposed, which are derived by using KIT (Kitami
Institute of Technology) satellite link site diversity databank with 108
datasets in 12 countries and thunderstorm ratio as a regional climatic
parameter [Ito et al., 2006].
B.
Effects of Other Factors
The measurement method used to extract
important statistical parameters for different propagation environments and
elevation angles is explained and discussed and results obtained from the
measured data are presented. These results are compared with those from other
empirical models given in the Rec. ITU-R P.681-6 to show the feasibility of
this technique in the study of Mobile Satellite (MS) link. The outcome of this
report will enable MS link data to be acquired from any region of the world for
any predefined environment of interest [Abidin et al., 2006a]. The measurement
method utilizing a portable GPS receiver used to extract important MS
propagation parameters is explained and discussed. Results obtained from the
empirical data and made comparison between various MS environmental conditions
were presented. [Abidin et al., 2006b, 2006c]. The analyses of the MS
propagation data obtained using the cost effective portable, commercial GPS
receiver was presented. The analyses results show the relationship between the
MS received signal performance and the ground blockages. The feasibility of
using GPS in the study of MS link performance is validated [Abidin et al.,
2007a].
Studies were carried out in equatorial
region (
(A. Sato)
F1.3
A.
Macrocell/Microcell Systems
A theoretical analysis method for
diversity gain is proposed assuming base station polarization diversity in
W-CDMA. The evaluation model used for theoretical analysis is verified based on
a comparison with the experimental results and the analytical results of the
practical diversity gain are clarified [Fukushige and Imai, 2007]. A channel
model for line-of-sight small street microcell in dense urban areas is
proposed. The scattering power distribution in the channel seen from the receiver
based on the physical phenomenon is obtained. The coefficients of the
distribution are derived by approximation to a set of urban street microcell
measurement data. The azimuth-power spectrum for the proposed model is compared
to those for conventional elliptical model as well as to the experimental
results obtained from measurements in three different streets of a dense urban
area. It is shown that the proposed model in contrast to the conventional
models produces results that closely agree with the experimental results
[Ghoraishi, et. al., 2006a]. A series of measurements in two streets in a dense
urban area were accomplished. The measurement scenario was small microcell
line-of-sight with low antenna height at both link ends where dipole sleeve transmitter
antenna, directive receiver antenna, wideband pseudo-noise signal and
correlator were employed. The data obtained from the measurements by careful
investigation of the single-bounce scattering power distribution conforming is
analyzed to precise maps of the environments including all present objects. The
single-bounce scatterers for the cluster received waves appearing in the
single-bounce scattering power distribution is identified. A number of objects
were identified by this method as single-bounce scatterers within the spatial
resolution bins. The identified objects are signboards, traffic signs, etc. and
it is concluded that any metallic object visible to both Tx and Rx with
dimensions in orders of tens of wavelengths can be a significant source of
scattering in small cell scenarios with low antenna heights. The contribution
of the scattering from these identified objects to the received power compared
to other micro-mechanisms is evaluated. Results show that the scattering from
these objects can be comparable to the wall reflections [Ghoraishi, et. al.,
2006b]. Based on a double directional measurement in a residential area of 
ground cover factors [Nishi et. al.,
2005]. Multipath propagation characteristics in a very large office with over
5000 of floor space were studied by
measurement and ray trace simulation. The results indicate that the method for
estimating the delay spread by using the floor space (Rec. ITU-R P.1238) is
applicable to such a large office. Cross-floor interference was also studied
experimentally. A coupling loss of approximately 20 dB on adjacent floors can
be expected for a modern building with large windows [Kita et al., 2005a]. A
new dynamic variation model of the delay profiles in LOS indoor environments
based on the measured delay profile snapshots in some LOS indoor environments
is presented. The difference between using the conventional and newly proposed
dynamic delay profile model based on the evaluation of the MIMO channel
capacity was also presented [Kita et al., 2005b]. Employing a shaped beam
pattern from a base station array antenna in the IMT-2000 system, e.g., a
cosecant beam pattern, is preferable because employing a shaped beam pattern in
a service area provides a sufficient received power level while imparting only
a slight interference power level to other areas. A simplified method for
shaping a beam pattern from the base station array antenna that maximizes the
downlink system capacity of W-CDMA in IMT-2000 systems is proposed. Calculation
results show that when 12.5% to 37.5% of the total number of array elements is
shifted 60 to 150 degrees, an increase in the system capacity of 180% to 190%
is achieved [Kimura et. al., 2006]. The characteristics are shown on the
measured path loss in the 800 MHz and the 5 GHz bands assuming the
macro-cellular environment where the base-station antenna is set on the roof of
a high building. The measured data indicates that the frequency dependence of
the path loss is almost the same as that in the free space. Using this result,
the applicable frequency range of the path loss prediction formula of the
Walfisch-Ikegami model is extended up to 5 GHz. The estimation errors in 5 GHz
band were greatly improved by the modified new formula [Yonezawa et. al.,
2005a]. It is expected that some higher frequency bands over 2 GHz will be used
for future mobile systems. In Rec. ITU-R P.1411, the prediction formula for the
over-rooftops environment, where the BS height exceeds the average building
height, was extended up to 5 GHz based on the measurements conducted in a
suburban city in
B.
MIMO Channel Modeling and Measurement Method
The statistical distribution of
eigenvalues of correlation matrices in i.i.d. MIMO Rayleigh fading channels is
presented. First, the statistical eigen-analysis of MIMO channel correlation
matrices is carried out, and the exact expression of the marginal distribution
of eigenvalues is presented. Then, a monomial approximation of above distribution
with a simple form convenient for the calculation of MIMO performance is
proposed based on the theory of space diversity in SIMO systems adopting
maximal ratio combining. Through computer simulations, the effectiveness of the
proposed approximation method is demonstrated. [Taniguchi et. al., 2005a and
2006] In MIMO communication systems, eigenvalues of channel correlation
matrices play an essential role for the performance analysis, and particularly,
the investigation about their behavior under time-variant environment ruled by
a certain statistics is an important problem. This paper presents an
approximation formula of the marginal distribution of all the eigenvalues of
MIMO correlation matrices under i.i.d. Rayleigh fading environment. The authors
show that the theory of SIMO space diversity using maximal ratio combining
(MRC) is applicable to the approximation of statistical distributions of all
eigenvalues in MIMO systems with same number of diversity branches. The derived
approximation has a monomial form suitable for the calculation of various
performance indexes used in MIMO systems. Through computer simulations, the
effectiveness of the proposed method is demonstrated [Taniguchi et. al.,
2005b]. A general approximation formula of the largest eigenvalue distribution
in correlated MIMO Rayleigh channels is presented. The proposed formula is
given by improvement of SIMO based analysis method of MIMO systems, and
applicable to any type of correlation including the case covariance matrix has
degenerated eigenvalues for which conventional exact formula could not be used.
The effectiveness of the proposed equation for various correlated MIMO channels
is demonstrated through computer simulations [Taniguchi et. al., 2007a]. An
approximation method of statistical distribution of the largest eigenvalue in
i.i.d. MIMO Nakagami-M fading channels is described. The given formulae are
introduced based on the conversion of MIMO channels into those of SIMO with the
same number of diversity branches. The derived density function has a simple
monomial form which is suitable for calculations of various performance indices
of MIMO systems. Through computer simulations, the effectiveness and problems
are discussed [Taniguchi et. al., 2007b]. An approximation method of statistical
distribution of the largest eigenvalue of i.i.d. MIMO channel correlation
matrices under Nakagami-Rice fading environment is presented. The equation is
actually derived for MIMO Nakagami-M fading channel which is known as a good
approximation of Nakagami-Rice fading, hence it well approximates the curves of
the largest eigenvalue distribution of non-central Wishart matrices. In the
proposed approximation method, MIMO MRC system is ascribed to SIMO space
diversity theory with the same number of branches, and the statistical
distribution becomes a monomial gamma distribution. As a result, the derived
marginal density function does not contain any special functions, and has a
simple monomial gamma form which is suitable for various calculations of
performance indices. Through computer simulations, it is shown that the
proposed approximation formula is effective and has a better precision than
conventional method [Taniguchi et. al., 2007c and 2007d]. 2x2 and 4x4 MIMO
channels were measured in LOS and NLOS indoor environments. Based on the
measured data, fading correlations were obtained. Also, the performance of
space division multiplexing and eigenbeam space division multiplexing were
clarified. [Ogawa et. al., 2005a and 2005b] Based on the measured data, eigenvalue
distributions were obtained, and channel capacity was calculated in a case
where the channel state information is available at a transmitter side. Also,
the bit error rate performance of eigenbeam space division multiplexing were
clarified [Nishimoto et. al., 2007]. 4x4 MIMO channels were measured in
time-varying LOS and NLOS indoor environments. Based on the measured data,
channel autocorrelations and Doppler spectra were obtained. Also, the bit error
rate performance of eigenbeam space division multiplexing were clarified [Bui
et. al., 2007a and 2007b]. There have been only a few MIMO propagation
characteristic studies that focus on antenna directivity under outdoor LOS
conditions. Therefore, MIMO propagation characteristics are measured for outdoor
mesh networking. And the results show that the MIMO with directional antenna
can improve channel capacity, and eigenvalue than that of MIMO with an
omni-directional antenna [Yamada et. al., 2005]. CSI (Channel State
Information) error becomes a factor to decrease the communication quality in
adaptive MIMO-OFDM system. The proposed empirical formula of prediction SIR
(Signal to Interference Ratio) based on the measurement which is the ratio
between the power of the eigenvalue and the interference power is proposed, so
as to evaluate the communication quality. This empirical formula of SIR is
possible to estimate the value of SIR by changing frequent correlation
coefficient [Yamada et. al., 2007]. In MIMO eigenbeam space-division
multiplexing, all transmission and reception antennas have been used to obtain
the maximum transmission performance. However, the absorbed energy is wasteful
when a part of the elements are blocked. A method is proposed for giving up the
use of unfunctional elements.
Result of ray tracing simulation showed that the proposed method
outperformed the conventional MIMO that always used all array elements
[Takahashi et. al., 2006]. The service area expansion of the data transmission
by MIMO is expected, therefore, expansion of service to isolated space is
expected through a repeater which has two or more relay antennas. This
propagation channel is Multi-Keyhole environment in equivalence. The keyhole
effects severely reduce the capacity of MIMO channel. However, if the number of
keyholes increases, this influence decreases. In this paper, the MIMO repeater
system and Multi-Keyhole Model are proposed, which realize the repeat function
to isolated space where communication of high data rate and high reliability is
needed. MIMO repeater system is supported the feature of MIMO function and
performance. Eigenvalue distributions, average channel capacity and average BER
performance of MIMO repeater channel are shown by computer simulation. Finally,
it is shown that the number of relay antennas required for the repeat which
keeps the function of MIMO [Tsuruta et. al., 2006]. MIMO leads to dramatic
improvement in channel capacity and/or link reliability of wireless systems.
However, a MIMO channel has only one degree of freedom in a keyhole environment.
As a result, this environment reduces achievable channel capacity and link
quality. This paper proposes a MIMO repeater system, which can realize a
multi-stream transmission. Although the averaged channel capacity in the MIMO
repeater system is discussed in several published papers, the probability
density functions of eigenvalues of correlation matrix are not analyzed. MIMO
transmission performance can basically be estimated from eigenvalues of the
channel correlation matrix. An approximated formula for the probability density
function of all eigenvalues linked to the space diversity is derived. It is
shown that the calculated values based on the proposed method agree very well
with the simulated values [Tsuruta et. al., 2007]. An overview of research in
channel modeling for MIMO data transmission focusing on a radio wave
propagation is provided. A MIMO channel is expressed as an equivalent circuit
with a limited number of eigenpaths according to the singular-value
decomposition (SVD). Each eigenpath amplitude depends on the propagation
structure not only of the path direction profiles for both transmission and
reception points but also of intermediate regions. Inherent in adaptive control
is the problem of instability as a hidden difficulty. In this paper these
issues are addressed and research topics on MIMO from a radio wave propagation
viewpoint are identified [Karasawa, 2005]. Recent antennas and propagation
studies for MIMO systems are reviewed. A MIMO propagation channel model is
firstly introduced in which an interesting nature can be found in eigenvalue
statistics from a practical viewpoint. Multi-keyhole model is then introduced
which is an efficient tool for designing a MIMO repeater systems, or MIMO
radio-relay systems. For realization of compact MIMO antenna systems,
effectiveness of using multiple polarizations such as dual polarizations and
triple polarizations is demonstrated in multipath-rich propagation
environments. With application of MIMO to OFDM systems, analysis on relation is
focused between propagation and digital transmission characteristics under a
severe multipath-rich environment where the delay profile exceeds the guard
interval. Finally, transmission characteristics of MIMO-OFDM with MRC diversity
in the environment are discussed [Karasawa 2007a]. A novel internal
multi-antenna configuration employing folded dipole elements for notebook PCs
is proposed. It is taken particular note of the properties of the folded dipole
antennas that eliminate the undesired current on the ground plane. Employing
folded dipole antennas in a multi-antenna configuration, mounted at the four
corners of the upper ground plane of a notebook PC model, resulted in an
approximate 5 dB increase in the pattern averaging gain compared to that for
inverted-L antennas, which are popularly used as internal antennas equipped in
mobile equipment. Furthermore, evaluated results of the multi-antenna
performance showed that the proposed quad folded dipole antenna configuration
achieves an approximate 6 dB higher beamforming gain and approximately double
the MIMO channel capacity, respectively, compared to those for a quad
inverted-L antenna configuration with a low correlation coefficient of less
than 0.2 [Okano and Cho, 2006]. The rapid growth in mobile communication systems
leads to a great demand for MIMO and multi-band systems to enhance the data
rate and the capacity of the radio network, thus both multi-antenna and
multi-band technologies must be employed for mobile terminals. In regard to the
link budget, the performance of antennas is a vital element since the
performance will not only affect the quality and the coverage of the mobile
network but also the capacity of the entire networks. Hence, clarification of
the performance of multi-band and multi-antennas mounted on actual mobile
terminals is currently urgently needed. This is especially true in practical
usage situations and since the size and style of mobile terminals has changed
significantly over the last several years. This paper presents the available performance
of multi-band and multi-antennas designed for 4x4 MIMO and triple-band
operation covering the 800 MHz, 1.7 GHz, and 2 GHz bands, when the antennas are
mounted on an actual mobile terminal. A multi-band folded inverted-L antenna is
firstly introduced in this study. Then the influence of mutual coupling,
implementation losses and multi-antenna performance are investigated when
employing the multi-band folded inverted-L antennas. The investigation is based
on the measurement in an anechoic chamber. The developed measurement facility
that employs the multi-channel antenna pattern measurement system enables us to
acquire the amplitude and phase patterns of multi-antennas at high speed [Okano
and Cho, 2007a]. The influence of the XPR of the waves arriving at a mobile
terminal on the MIMO channel capacity in multi-band and multi-antenna
configurations is investigated. The propagation environment around a mobile
terminal is assumed extremely diverse in future mobile communication systems.
This is because it is desirable to support flexibly indoor areas as well as
outdoor areas using the same air interface, and diverse antenna configurations
will be employed for the base station such as space diversity configurations
and polarization diversity configurations. This paper is aimed at evaluating
the channel capacity for multi-frequency bands under the conditions of free
space and in the data mode. An actual handheld device as a mobile terminal and
we mount onto the handheld device unique antennas for MIMO transmission
designed for multi-band operation is employed. Furthermore, the dependency of
channel capacities on the XPR is quantitatively analyzed using detailed
parameters including the mean effective gain (MEG), the correlation coefficient
between antennas, and the eigenvalue of the correlation matrix based on the
measured radiation patterns. As a result, it is shown that a low absolute XPR
of the arriving waves increases the channel capacity for all frequency bands
due to the dual-polarized properties of the antennas mounted on the handheld
device [Okano and Cho, 2007b]. In MIMO eigenbeam space-division multiplexing,
all transmission and reception antennas have been used to obtain the maximum
transmission performance. However, the absorbed energy is wasteful when a part
of the elements are blocked. A method is proposed for giving up the use of
unfunctional elements. Result of ray tracing simulation showed that the
proposed method outperformed the conventional MIMO that always used all array
elements [Takahashi, et. al., 2006].
C.
Formulation of Mobile Propagation
A site-general type prediction formula
is investigated based on measurement results in an urban area in Japan assuming
that the prediction frequency range required for the Fourth - Generation (4G)
Mobile Communication Systems is from 3 to 6 GHz, the distance range is 0.1 to 3
km, and the range in the base station height is from 10 to 100 m. Moreover, a
correction formula for suburban areas is proposed based on the difference
between calculated values using the prediction formula for urban areas and the
received levels measured in the suburban area [Kitao and Ichitsubo, 2006].
Frequency dependence for spatial dispersion of radio wave arrived at base
station was measured in 0.4, 2 and 8 GHz on urban area. It is made clear by
measurement results that spatial dispersions do not depend on frequency and are
the same in 0.4 to 8 GHz band [Kitao and Ichitsubo, 2007]. A statistical
scattering model for mobile radio channels is proposed that has three features:
1) the effective scattering area is expressed by an ellipse the center of which
is the MS location; 2) the major axis of the ellipse runs parallel along the
street where the MS is located; and 3) the scattering power density function
around the MS is expressed by a combination of two Laplacian distributions in
which the standard deviations are different [Imai and Taga, 2006]. Multi-path
phase difference distribution in a narrow mobile radio channel was studied on a
domain and frequency axes using theoretical and simulated results. The
multi-path phase was discussed in great detail by using the cumulative
distribution, and both theoretical and simulated results were showed good
agreement with a wide range of 0.001 to 99.999 %. Furthermore, a new phase
difference cumulative value locus was devised. For the applications, using the
cumulative value enabled the M-ary DQPSK-BER to be estimated and using the
locus enabled a pilot signal on the domain to be allocated flexibly [Kozono
2007]. The urban physical propagation environment around the mobile station is
often described as a multipath environment, where power is received through
diffractions over rooftops and building corners, reflections from walls and
scattering in general from other surrounding objects. Since there is only
finite number of these scatterers, the waves are received in clusters each
originating from one of the scattering sources. To study these scatterers,
direction-of-arrival data measured along continuous routes in two small
macro-cellular environments were analyzed. Multipaths received with
approximately the same directions and delays were combined as clusters.
Therefore each of the clusters corresponds to the signal received from one
scatterer. This paper focuses on both the identification of the physical
scatterers in the surrounding environment and studying the radio wave
propagation in more detail, including the amount of significant scatterers in
terms of contributed power, XPR values, and delay and azimuth spreads of the
individual clusters. The results show that there are only a few dominant
scatterers. They were usually building corners and walls, and building
structures over the rooftop level. The delay and azimuth spreads inside the
clusters were small, and depolarization was almost negligible. Both propagation
over the rooftop level and propagation along the street canyons were
significant in the considered environments [Vuokko, et. al., 2005]. The
polarization behavior of the mobile MIMO radio channel is analyzed from
polarimetric double-directional channel measurements, which were performed in a
macro-cell rural environment in Tokyo. The recorded data comprise
non-line-of-sight, obstructed line-of-sight, and line-of-sight conditions. The
gradient-based maximum-likelihood estimation framework RIMAX was used to
estimate both specular and dense multipath components. Joint angular-delay
results are gained only for the specular components. The dense multipath
components, which may be attributed to diffuse scattering, can be characterized
only in delay domain. Different characteristics describing the polarization
behavior and power-weighted cross- and copolarization ratios for both types of
components are introduced. Statistical analysis of long measurement track
segments indicates global trends, whereas local analysis emphasizes specific
behavior such as polarization dependency on angle of incidence in streets and
under shadowing conditions. The results also underline the importance of
modeling changing and transient propagation scenarios which are currently not
common in available MIMO channel models [Landmann, et. al., 2007]. Results of
measurements carried out at distances ranging from approximately 5 to 30 km are
presented. In these measurements, frequencies in the 2 GHz and 5 GHz bands are used
simultaneously to investigate the difference in path loss between the 2-GHz
band and 5-GHz band. The difference in path loss is approximately 7 to 9 dB
based on the analysis of these measured data for median values in 10-m
intervals. The results enable us to estimate the path loss for the 5-GHz band
from that of the 2-GHz band [Sato, et. al., 2005]. A new method for predicting
the path loss in over-rooftop propagation environments in microwave bands is
proposed. In the paper, it is clarified that the path loss due to distance can
be divided into three regions where the direct wave, the reflected wave, and
the diffracted wave are dominant, respectively. The validity of the model is
tested by measuring the path loss at 2.2 GHz, 5.2 GHz, and 19.4 GHz (CW) in
suburban areas in Tokyo [Kita et al., 2006a, 2006b]. A height variation model
at subscriber station (SS) in the region more than 4 m high, which is reflected
the dependency on location of SS for FWA/NWA systems in microwave band in
suburban areas, is proposed. The validity of the model was tested by
measurements of the height variation at SS in 2.2 GHz, 5.2 GHz, and 25.15 GHz
(CW) in suburban areas in Japan [Kita, et al., 2007]. Propagation studies and
models that are expected to contribute to the development of broadband wireless
systems are surveyed and introduced. The survey focused on theory-based
propagation models, experimental measurement data useful for modeling, and
transmission characteristic evaluations using propagation models. The survey
did not attempt to cover all papers in the research fields, but rather took key
papers for various relevant subjects and described them in some detail. The
basic characteristics of multipath propagation are summarized from the
viewpoints of narrow-band (NB), wide-band (WB), and ultra wide-band (UWB).
Recent studies on spatio-temporal propagation models and the relationship
between models and systems are introduced. To clarify the relationship between
OFDM, which is a representative of wideband data transmission schemes, and wave
propagation factors, problems due to large delay spread and large Doppler
spread are highlighted. Finally, studies on UWB propagation measurement and
propagation models are introduced [Karasawa 2007a]. Theoretical analyses on
level variation of wideband signals in Rayleigh fading environments are carried
out. The model is based on eigenvalue analysis in frequency domain which is a
new approach for making clear the characteristics theoretically [Inoue 2005].
In order to assess the effect of multipath fading on OFDM signal transmission
when the delay profile exceeds the guard interval, a simple prediction model is
developed based on the Equivalent Transmission-Path (ETP) model. This model,
which is described in this paper, is referred to as the ETP-OFDM-statistical
model. The validity of the model is demonstrated by comparing the calculated
digital transmission characteristics to results obtained by computer
simulation. Using the newly developed ETP-OFDM-statistical model, digital
transmission characteristics of the OFDM signal in a multipath environment when
the delay profile exceeds the guard interval are shown as a function of delay
spread, guard interval and OFDM symbol period [Karasawa, et. al., 2005].
D.
Ultra Wideband
The concept of measuring double
directional channels in UWB systems is introduced. Antenna-independent channel
data were derived by doing the measurements in a wooden Japanese house. The
data were useful for investigating the impact of UWB antennas and analyzing
waveform distortion. Up to 100 ray paths were extracted using the SAGE
algorithm and they were regarded as being dominant. The paths were then
identified in a real environment, in which clusterization analyses were done
using the directional information on both sides of the radio link. Propagating
power was found to be concentrated around the specular directions of reflection
and diffraction. This led to the observation that the spatio-temporal
characteristics of extracted paths greatly reflected the structure and size of
the environment. The power in the clusters indicated that the estimated 100
paths contained 73% of the total received power, while the rest existed as
diffuse scattering, i.e., the accumulation of weaker paths. The practical
limits of path extraction with SAGE were also discussed. Finally, it is derived
that the scattering loss and intra-cluster properties for each reflection
order, which were crucial for channel reconstruction based on the deterministic
approach [Haneda, et. al., 2005a]. Results from propagation channel
measurements in a Japanese wooden house is reported. With the measured data,
following analyses were conducted: 1) extraction of 100 waves using SAGE
algorithm; 2) clusterization of the detected paths in a heuristic approach; 3)
investigation of the spatio-temporal cluster characteristics including path
identification; and 4) consideration on the residual components [Haneda et.
al., 2005b]. Results from measurement of UWB double directional channels in a
standard Japanese wooden house are presented. Channel parameters which
characterize the behavior of channels were introduced. The parameters help us
not only interpret physical phenomena intuitively but also contribute to the
antenna-independent channel models quantitatively [Haneda, et. al., 2005c]. The
link budget evaluation scheme is proposed for UWB system based on the extended
Friisf transmission formula. The template waveform is considered at the
receiver side to maximize the SNR for evaluation. An experimental evaluation of
the antenna transfer function needs the three types of broadband antennas. The
technique gives very accurate results and is very useful for design and
evaluation of UWB impulse radio transmission systems, especially for the
evaluation of waveform distortion effects [Promwong and Takada 2005]. An UWB
channel sounding scheme with a parametric channel estimation to seek accurate
probing of the propagation channel. The channel sounder consisting of a vector
network analyzer and synthetic array to measure spatial transfer functions is
presented. The measured data are then applied to a maximum-likelihood
(ML)-based estimator. The concepts implemented in the ML-based parametric
channel estimation are: 1) to probe frequency-dependent effects in magnitude and
phase of propagation paths and 2) to incorporate with robust concept of
direction finding, namely, the spherical wavefront model of incident waves. The
whole frequency band was divided into subbands, and the estimation of magnitude
and phase was conducted in each subband. The spherical wavefront model includes
a new model parameter, curvature radii, which is not covered in the
conventional plane wavefront model. Performances of the proposed parametric UWB
channel estimation scheme were assessed by anechoic chamber tests. The test
demonstrated that: 1) the frequency-dependent magnitude and phase were
accurately detected if the path was resolved and 2) the spherical wavefront
outperformed the plane wavefront to model measured data given the short-range
environment. Furthermore, fundamental performance of the sounding scheme, i.e.,
angular and time resolutions, was also evaluated in the test [Haneda, et. al.,
2006a]. An UWB double-directional channel sounding measurement and
spatio-temporal analysis of UWB propagation based on the clusterization
approach were reported. After separating the propagation paths and diffuse
components both on the transmitter antenna and receiver antenna positions, the
propagation paths both on Tx and Rx positions were observed for clusters
separately, while coupling the clusters between Tx and Rx position based on
similar time of arrivals, and ray tracing by utilizing high temporal and
spatial resolution, respectively. The relation between direction of departure
and direction of arrival will then be investigated. For cluster properties,
parameters of model characteristics are discussed and compared to other earlier
works [Tsuchiya, et. al., 2006]. Results from double directional UWB channel
sounding in a wooden house are described. The double directional channel
sounder estimates directional information at both ends of the link, so that
antenna directivity can be separated from the channel sounding results. The
dominant propagation mechanisms are investigated by introducing cluster analyses.
The detected propagation paths from the channel sounding were first classified
into clusters in the angular-delay domain, and then properties of the clusters
such as standard deviation of path positions, dynamic range of path power, and
power distribution of clusters were derived. From the results, the similarities
and differences are discussed between the measurement environment and the
physical propagation phenomena. Finally, different types of scattering losses
of the propagation paths were derived and modeled. The results from sounding
and analysis contribute in the development of UWB propagation models and can be
used in UWB propagation simulations [Haneda, et. al., 2006b]. The verification
of the effectiveness of stored channel simulations for evaluating UWB
communication system performances is described in realistic propagation
environments. It was achieved by investigating the similarity of two received
waveforms: one acquired by the real signal transmission and the other
reconstructed using stored channel simulation. The actual received waveform was
directly measured by a UWB testbed. On the other hand, the transfer function of
the antennas and propagation channels measured by a vector network analyzer,
i.e. the stored channel, together with the transfer functions of the
transmitter and receiver of UWB testbed, were used in simulation to reconstruct
the received waveform. The result shows that the actual measured received
waveform is almost identical to the reconstructed received waveform via stored
channel simulation [Haneda, et. al., 2007]. Numerical analyses are presented of
the effects of errors realized in complex relative permittivity, in order to
give guidelines for synthesizing UWB electromagnetic phantom materials. Liquid
and solid recipes were developed through possessing the permittivity of
high-water-content human tissues within tolerable errors [Hara and Kobayashi
2005]. Ultrawide-band channel sounding scheme is proposed with a technique for
estimating time of arrival (TOA) and angle of arrival (AOA) using an antenna
array time domain smoothing. Experimental validation of the scheme was also
presented [Iwakiri and Kobayashi 2007]. Ultra wideband signal propagation was
measured and characterized in comparison with narrowband in a passenger-car
compartment. Whereas narrowband channels resulted in a number of dead spots
(deep fading points), UWB (3.1 to 10.6 GHz) yielded none, though some frequency
dispersion was inevitable. Fading depth versus occupied bandwidth was derived,
which indicated superiority of UWB over narrowband systems from the viewpoint
of link budget [Kobayashi 2006a, 2006b]. An automated ellipticity measurement
system is described for UWB circular polarization antennas. Ellipticity and
wideband XPD of an axial-mode helical antenna were measured using this system
[Maeda and Kobayashi 2005]. An omni-directional in azimuth, low VSWR, and
easy-to-construct antenna was proposed for UWB systems. [Maeda and Kobayashi
2007] Results were presented from ultra wideband propagation channel
measurements in an office environment at the 26 GHz band. To evaluate the
differences in a multipath environment by antenna radiation pattern, two
directional types of receiving antenna were used. The influence of the
multipath can be reduced by using a direction [Rikuta, et. al., 2006].
Short-range propagation measurements were carried out using UWB and CW signals
on a rectangular conductive plate, simulating typical office desks, with and
without a low vertical metal partition panels. The effects of human bodies were
also experimentally evaluated [Suzuki and Kobayashi 2005]. Ultra wideband
double directional channels were modeled as the sum of ray paths. The paths
were characterized by direction of departure, direction of arrival, and delay
time of arrival. The complex amplitudes of the paths were modeled as a function
of the frequency and represented by the values for subbands. These parameters
were estimated by using a SAGE-based algorithm. [Takada, et. al., 2005] An
omni-directional in azimuth and low VSWR (< 1.3 from 3 to 20 GHz)
ultra-wideband monopole antenna is reported. Performance comparison was made
between a prototype antenna and other representative wideband antennas
[Taniguchi, et. al., 2006]. The development of liquid UWB electromagnetic phantom
material and UWB arm and torso phantoms are presented [Zhou, et. al., 2006a,
2006b].
E.
Intelligent Transportation System (ITS)
Assuming inter-vehicle radio
communication systems (V2V), the propagation characteristic in non
line-of-sight intersections is analyzed and the results of the analysis are
shown. The propagation loss characteristics are evaluated using ray-tracing
technique when various system and environmental parameters, such as carrier
frequency, road width, building material and so on, are varied. In Japan, a new
spectrum allocation to ITS services in the 700MHz band is now considered.
Therefore the frequency characteristics of the propagation loss in the
environments are one of the main themes of the study. Based on the analyzed results,
the influence of the variation of the parameters on the propagation
characteristics is presented [Tango, et. al., 2007]. Electronic Toll Collection
(ETC), an application of Dedicated Short Range Wireless Communication (DSRC),
had suffered from wrong operations due to multipath problems. To solve this
problem, it is proposed to apply a simple configured path determination scheme
for the ETC system. The system consists of a vector network analyzer, low-noise
amplifier, and X-Y positioner and achieves an automatic measurement of the
spatial transfer function with emphasis on accurate measurement and
reproducibility. For the reliable identification of the propagating paths, 3-D
Unitary ESPRIT and SAGE algorithms were employed. Having developed the system,
field experiments at the toll gate of the highway was carried out. In the
measurements, it is possible to determine many propagation paths so that the
dominant propagation phenomena at the toll gate was identified. They included a
ground-canopy twice reflected wave, which was a potential path that caused
wrong operation. Consequently, their reflection coefficients and polarization
characteristics were investigated. From the results, applicability of the path
determination system for short range on-site measurement was confirmed [Haneda,
et. al., 2004]. The prediction of received power in the out-of-zone of a DSRC
system operating inside a typical arched highway tunnel is discussed. By
conducting wideband directional channel sounding inside the tunnel, the gain,
angle-of-arrival and delay of each propagation path are estimated by means of a
multidimensional maximum likelihood estimation algorithm from the measured
data. Using these estimated parameters and by employing simulations of
application antennas according to the DSRC standard, the received power in the
out-of-zone is predicted for 2 roadside unit (RSU) antenna positions. The
dominant scatterers causing the over-reach of radiated power to the out-of-zone
were identified and attributed to the ground and sidewalk. These scatters can
affect the received power level in the out-of-zone by as much as 10 dB. It can
therefore be concluded that suppressing ground and sidewalk scatterings in the
vicinity of RSU by installing composite pavement materials are needed to
increase the electromagnetic absorption in order to guarantee DSRC services
[Ching, et. al., 2007a, 2007b].
F.
Others
Accelerating the ray-tracing process
while maintaining a high level of prediction accuracy is an important problem.
In order to solve the problem, this paper proposes the ray-tracing acceleration
technique employing the genetic algorithm or GA. Its performance is also
evaluated by computer simulation [Imai, 2006a, 2006b].
Earthquake observation using radio waves has started from
1998. During the observation period, co-seismic EM phenomena have been observed
on three earthquakes, Tottori-ken-seibu earthquake in 2000, Geiyo earthquake in
2001 and Ibaraki-ken-oki earthquake in 2002. The observation method and
co-seismic observation results associated with the earthquakes are presented
[Yoshida, et. al., 2006]. A big earthquake occurred on October 23 in 2004,
which is called the Mid Niigata Prefecture earthquake. FM tuners located at
Nobeyama received the FM radio wave of 82.3 MHz broadcasted from FM Niigata
radio station. They detected EM anomalies before the earthquake. The
observation has been continued until now in order to clarify weather the
anomalies were pre-seismic phenomena or usual tropospheric phenomena such as
duct propagation. In the paper, the observation method and propagation
characteristics of FM radio waves of 82.3 MHz measured for three years at
Nobeyama observatory are described [Yoshida, et. al., 2007]. One approach to
discern whether the noises originated from earthquakes or others is
longstanding observations. Long term accumulating the data of EM waves can
reveal the ordinal properties of EM waves at the observational sites. The
characteristic features of EM waves vary in time, from day to day and according
to seasons. Accurate grasp of EM waves over short and long spans is a matter of
importance for exploration of the EM phenomena related with the earthquakes. In
this paper, the properties of FM radio waves at Niijima in 2006 are reported.
The ordinary states of FM waves in Niijima are helpful for discussion of the EM
phenomena related with the possible future earthquakes in this area [Takahashi,
et. al., 2007].
The characteristics of UHF band radio
propagation over the Seto Inland Sea is investigated in order to obtain primary
data to estimate interferences of the terrestrial digital TV system that will
be operated in UHF band. The authors have measured UHF band TV broadcasting
waves from the Matsuyama station at two observatories in Hiroshima prefecture
since June in 2005. From the measurement data, it was clarified that short-term
fading with a duration time less than 1 hour frequently occurred in summer
season and that long-term fading related to sea level fluctuations occurred in
winter season. It was also found that the received level became stable when the
typhoon with strong winds hit the propagation paths [Nishi, et. al., 2006a].
New indoor human detection systems using VHF-FM and UHF-TV
broadcasting waves are studied. In order to investigate the ability of VHF-FM
and UHF-TV human detection systems and compare these systems, the received
levels of VHF-FM and UHF-TV broadcasting waves in the room with or without
human presence are measured. Consequently, both VHF-FM and UHF-TV detection
systems could sense the human presence using an appropriate threshold of the
received level fluctuation. And the monitoring period of only 5 seconds could
achieve 100 % detection probability in both VHF-FM and UHF-TV detection systems
[Nishi, et. al., 2006b].
A new human detection system using UHF
band TV receiving waves is proposed. By use of the TV broadcasting waves as
radio transmission waves, the proposed system does not need a transmitter; the
system is composed of only receiving systems including a receiving antenna and
a receiver. The proposed system can detect the presence or absence of human in
a room based on the principle that the received level is fluctuated due to
multi-path fading or shadowing with human presence. Remarkably, the proposed
system utilizes the indoor multi-path propagation of UHF band TV broadcasting
waves to detect human presence. In order to investigate the human detection
abilities of the new system, in this study, the received levels of UHF band TV
waves are measured in the room with or without human presence [Nishi, et. al.,
2006c].
Reduction of AOA estimation error owing to amplitude and
phase perturbation in the array response using spatial smoothing preprocessing
(SSP) is proposed. The performance improvement of the proposed method is
validated by Monte-Carlo simulation. To show applicability of the proposed
method in practice, it was applied to estimate AOAs of measured data obtained
in an anechoic chamber and in an open site. According to the results, SSP can
reduce the random error in the array response, thus reducing the error of
estimated AOAs in the measured data [Cherntanomwong, et. al., 2006] .
(H. Iwai)
F2
Remote Sensing
F2.1
Atmosphere
In this section, the
remote sensing of atmosphere from the ground to the altitude of about 100 km is
reviewed.
A.
GPS meteorology
GPS (Global Positioning System) meteorology is a sounding
technique of the atmosphere, by measuring propagation delay time of radio waves
transmitted by GPS satellites. It provides us with information of electron
density in the ionosphere, temperature in the stratosphere and humidity (water
vapor) in the troposphere. The receiver could be located on the ground, ship,
airplane, or satellite. A global observation of atmosphere with a very high
vertical resolution can be obtained by LEO (Low Earth Orbit) satellite with the
radio occultation method. Such LEO measurements (e.g. CHAMP, SAC-C) have been
used to study characteristics of tropopause, Kelvin and gravity waves in the
troposphere and stratosphere, and so on [Ratnam et al., 2005; Ratnam et al.,
2006a; Ratnam et al., 2006b; Tsuda et al., 2006]. Recently a huge number of LEO
measurements become available due to the COSMIC (Constellation Observing System
for Meteorology, Ionosphere, and Climate) mission (providing over 2,000/day soundings
by 6 LEO satellites) and are expected to improve numerical weather forecasts by
data assimilation.
B.
Various techniques of observation in troposphere with MST radars
The angular and range resolutions of MST
(Mesosphere-Stratosphere-Troposphere) radars (or wind profilers) are often
limited by their beamwidth and system bandwidth, respectively. The
high-resolution imaging techniques with the Capon processing method have been
developed based on multi-receiver and/or multi-frequency interferometry using
the MU radar (Middle and Upper Atmosphere Radar of Kyoto University) [Luce et
al., 2006]. The high-resolution images have clarified the detailed structure of
thin layers above the convective cells and of Kelvin-Helmholtz billows [Luce et
al., 2007]. The Capon method was utilized to reduce ground clutter from the MU
radar data [Kamio et al., 2004] and the Equatorial Atmosphere Radar (EAR) data
[Nishimura et al., 2006].
Most contemporary wind profilers utilize
the Doppler beam swinging (DBS) method to estimate horizontal wind from three
(two adjacent oblique and one vertical) or four oblique beams. Adachi et al.
[2005] showed that the four-beam method has better accuracy and precision of
wind speed because the four-beam method is less susceptible than the three-beam
method not only to patchy rain, but also to the vertical airflow with spatial
variability.
The Japan Meteorological Agency (JMA)
started operation of a wind profiler network called the WInd profiler Network
and Data Acquisition System (WINDAS) in 2001 [Ishihara et al., 2006]. WINDAS is
unique in that it uses 31 1.3-GHz profilers having the spatial resolution of
130 km on average. Tropical cyclones were observed with the WINDAS radar at
Naze,
The 47-MHz Equatorial Atmosphere Radar
(EAR) has been operated at Kototabang, West Sumatra, Indonesia since 2001 and
has been very successfully used for the study of equatorial atmosphere
dynamics. A research project called Coupling Processes in the Equatorial
Atmosphere (CPEA) was conducted for studying the coupling processes in the
equatorial atmosphere during 2001-2007 [Fukao 2006]. Various instruments,
including rawinsonde balloons, X-band meteorological radars, meteor radar, MF
radars, and Rayleigh/Mie lidar, have been assembled at and around the EAR site
to cover as wide a height range. Direct evidence that atmospheric gravity waves
are generated by deep cumulus convection was obtained with the EAR [Dhaka et
al., 2005, 2006; Alexander et al., 2006]. The features of vertical motion have
been revealed based on the EAR observations [Seto et al., 2006; Mori et al.,
2006; Yamamoto et al., 2007; Nishi et al., 2007]. Atmospheric dynamics and
raindrop size distribution observed with the EAR have been investigated [Seto
et al., 2004; Sakurai et al. 2005; Renggono et al., 2006; Shibagaki et al.,
2006a, b; Murata et al., 2006].
C.
Mesosphere and Lower Thermosphere (MLT) Region
Mesosphere and lower thermosphere region
exhibits special interests because it is a transient region between the neutral
and ionized atmospheres, and eddy diffusive and molecular diffusive
atmospheres. Variability of this region has been studied intensively by using
ground-based/space-borne observations, modelings and theoretical works.
As for the observational study, two
topics should be emphasized. The first is the very successful studies on
equatorial region with CPEA (Coupling Processes of Equatorial Atmosphere)
studies, which is a six-year project started in 2001. After the development
phase of the equipment and observational network, a huge amount of
observational results has become available from this project. MLT radar
observation has clarified correlation between MLT diurnal tides and Elnino
Southern Oscillation (ENSO) [Gurubaran et al., 2006]. Planetary scale waves
with period of 5-8 days have been studied in detail by combining MLT radars and
TIMED satellites [Sridharan et al., 2006]. Long-term trend of MLT winds have
also clarified with the MF radar [Sridharan et al., 2007]. Combined observation
with a metallic atom resonance lidar and a meteor radar has shown that
occurrence of sporadic sodium layer at the equator is very different from what
has been observed at mid latitude [Shibata et al., 2006]. Motion of E-region
irregularity and neutral wind has been studied with the meteor radar and EAR
(Equatorial Atmosphere Radar) over the equator [Patra et al., 2007].
Semidiurnal tides were studied with meteor radars, GCM (general circulation model)
modeling and TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics)
satellite observations [Du et al., 2007].
The second is radio-optical observations
using the MU radar and Shigaraki MU observatory, of
D.
Radio Acoustic Sounding System (RASS)
Radio Acoustic Sounding System (RASS) is
a radar remote-sensing technique to monitor high-temporal resolution
temperature profiles by combining a wind profiling radar (WPR) and ground-based
acoustic transmitters. The transmitted acoustic pulses produce atmospheric
refractive index fluctuation, which scatters radio-wave transmitted from a WPR.
Atmospheric virtual temperature is calculated from the Doppler shift of the
back-scattered radio signal. The RASS system for the MU (Middle and Upper
atmosphere) radar (the MU radar-RASS) can obtain the temperature profiles in
the troposphere and lower stratosphere with the temporal resolution of a few
minutes. The temperature profiles were used to investigate the effect of
atmospheric stability on the wave propagation and the detailed temperature
fluctuation across the tropopause [Alexander et al. 2006, 2007]. The RASS technique
developed for the MU radar was applied to the other radar systems such as
1.3GHz- and 400MHz-wind profiling radars and the Equatorial Atmosphere Radar
(EAR) to monitor temperature profiles in the boundary layer and the tropical
region [Furumoto et al. 2005, 2006; Imura et al., 2006]. Humidity profiles can
be estimated from the turbulence echo and RASS observation data and
successfully revealed the detailed structure of wind, temperature and humidity
profiles during the passage of raincloud [Furumoto et al., 2005, 2007].
E.
Spaceborne Sensors
The Greenhouse gases Observing SATellite
(GOSAT) will observe the concentrations of carbon dioxide and methane, two
major greenhouse gases, from space. GOSAT project is a joint effort of JAXA,
Ministry of the Environment, and the National Institute for Environmental
Studies (NIES). The observation instrument onboard GOSAT is called the Thermal
and Near-infrared Sensor for Carbon Observation (TANSO). TANSO is composed of
two sensors: a Fourier transform spectrometer (FTS) and a cloud aerosol imager
(CAI). Band 1 (0.76 µm), Band 2 (1.6 µm), and Band 3 (2.0 µm) of FTS will
provide the spectra of sunlight reflected from the earthfs surface in the
daytime, and Band 4 (5.6 -14.3 µm) will observe light emitted from the
atmosphere and the earthfs surface throughout the day and night. The imagery
data from TANSO-CAI will be used to determine the existence of clouds and to
estimate aerosol parameters over a wide area. Several environmental tests of
the proto-flight model of the TANSO sensor were preformed in 2007. Data
retrieval algorithms of carbon dioxide and methane concentrations under the
almost clear-sky conditions in operational data processing have also been
developed by 2007.
JAXA and NICT are collaborating to develop a space-borne
submillimeter-wave limb sounder called Superconducting Submillimeter-Wave
Limb-Emission Sounder (SMILES) to be aboard the Japanese Experiment Module
(JEM) of the International Space Station. JEM/SMILES is designed to observe
global three dimensional distributions of stratospheric ozone-depletion-related
gases such as O3, ClO, BrO, HCl, HNO3, and HO2 in submillimeter-wave bands
around 640 GHz by a highly sensitive SIS (Superconductor-Insulator-Superconductor)
receiver operating at 4.5K. Simulation studies based on the detailed
instrumental design have performed its capability of retrieving stratospheric
minor constituents [Kasai et al., 2006]. The Balloon-Borne SMILES (BSMILES) was
developed for the development of SMILES and data analysis software. Two flight
experiments of BSMILES demonstrated advantages of low noise submillimeter-wave
limb-sounder to the stratospheric observation. A weak stratospheric HO2 signal
was detected by BSMILES [Irimajiri et al, 2006]. Stratospheric ozone and ClO
were also successfully observed by the BSMILES. Calibration and data analysis
of submillimeter-wave limb observation were studied. Retrieved profiles from
BSMILES observation show reasonable agreement with other available stratospheric
measurements [Ochiai et al, 2005].
F2.2
Hydrometeors and Other Particles
A.
Ground-based remote sensing studies
The information of raindrop size
distribution (DSD) is essential to improve the accuracy of radar rainfall
remote sensing. Seasonal and diurnal variation characteristics of tropical DSD
was extensively studied using disdrometer data at South India,
Precipitation studies with wind
profilers, which are normally considered to be clear-air instruments, have
proved to be quite interesting. A retrieval method (ITRAN) for DSD from Doppler
spectra measured with a wind profiler was proposed by Kobayashi and Adachi
[2005]. Bringi et al. [2006] compared rainfall parameters estimated from a
C-band polarimetric radar with those retrieved from the 443-MHz radar.
A 35-GHz radar to observe smaller
particles such as clouds and fogs has been developed and revealed the moving
cellular structure and shear-induced roll structure of fog echoes, and the
influence of gravity waves on fog structure [Uematsu et al., 2005a, b, 2007].
The cirrus clouds were simultaneously observed with the 35-GHz radar and the MU
radar [Wada et al., 2005].
B.
Space-based remote sensing studies
The TRMM (Tropical Rainfall Measuring
Mission) Precipitation Radar (PR) has a capability to estimate a path-averaged
DSD parameter for moderate to intense rainfall cases. Kozu et al. [2006b]
presented global characteristics of the DSD parameter estimated from TRMM PR,
which shows a clear contrast between over land and over ocean, and a clear
correlation with rain-top height and lightning activity. Most bright band (BB)
models face a problem at the BB top, where the assumed DSD is very different
from that of typical snow. To solve this problem, a new BB model is proposed.
The model assumes a linear change of precipitation rate with height and also a
linear change in slope of DSD with height in the upper part of BB. A comparison
of the model with an averaged height profile of radar reflectivity factor, Z,
obtained by the TRMM precipitation radar shows a good agreement [Awaka et al.
2006].
The Global Precipitation Measurement
(GPM) mission is a satellite-based Earth science mission that will study global
precipitation and provide accurate rain distribution over the globe more
frequently by using multiple satellites and better sensors than what are
currently available. The Dual-frequency Precipitation Radar (DPR), which is one
of the two key sensors on the core satellite in the mission, has been developed
jointly by JAXA and the National Institute of Information and Communications
Technology (NICT) in
A Cloud Profiling Radar (CPR) will be
installed on satellite mission named Earth Clouds, Aerosols and Radiation
Explorer (EarthCARE). EarthCARE mission, proposed by European and Japanese
scientists, has been selected for implementation as sixth Earth Explorer
Mission of European Space Agencyfs, focuses on clouds and aerosols effect on
the earth radiation flux budget. EarthCARE/CPR is millimeter-wave radar which
has high sensitivity. Radar frequency is the same as CloudSat CPR (94GHz)
launched in 2006 by NASA, but radar sensitivity is about ten times better
because of the lower orbit and bigger antenna size. It is anticipated to detect
98 % of radiatively significant ice clouds and 40 % of stratcumulous. Vertical
range of observation will be 20, 16, 12 km depending on the latitude.
Minimizing observation window is necessary to achieve higher pulse repetition
frequency (PRF) for accurate Doppler measurement.
JAXA is developing the Advanced
Microwave Scanning Radiometer-2 (AMSR2). AMSR2 will be onboard the GCOM-W1
satellite, which is the first satellite of the
C.
Others
A computer simulation of backscattering
enhancement from randomly distributed spherical scatterers was made at 30 GHz
[Oguchi and Ihara, 2006]. The simulation model was constructed to follow
exactly the scattering environment used in the laboratory measurements made
previously. The spherical wavefront and the directivity functions of
transmitting and receiving antennas were taken into account. The simulation
results agreed favorably with measurements for both copolar and cross-polar
channels. It was also shown that the multiply scattered power in backscattering
direction depends on the footprint size of a radar beam.
F2.3
Ocean and Ice
A method
for estimation of the backscatter coefficient of the sea surface, which is needed
for estimation of the sea wave period, is evaluated by a computer simulation.
By utilizing the property that the average received power ratio directly
represents the backscatter coefficient ratio, it is shown to be possible to
estimate the sea wave period. It is also shown that the average received power
can be derived with sufficient stability if the simulation parameters are set
appropriately [Fukuda, et al., 2006]
When multilook processing is applied to produce SAR images
of ocean, partially-overlapped sub-apertures are often used, because the
overlapping area is considered as uncorrelated due to short decorrelation times
of small-scale ocean waves which are responsible to radar backscatter. However,
a detailed theory showed that the decorrelation times of small-scale ocean
waves do not enter the inter-look speckle correlation, that is, the inter-look
speckle patterns are correlated if partially overlapped sub-apertures are used;
the theory was justified by the experimental analyses of JERS-1 L-band SAR and
RADARSAT-1 C-band SAR over the waters around Japan [Ouchi and Wang 2005a,
2005b, Wang and Ouchi 2005].
For the Korean Coast Guard, determination of the coastal
morphology in the shallow waters of the western coast of the
F2.4
Land, Vegetation, Subsurface Objects and Others
A.
Land and Vegetation
Pi-SAR, a fully polarimetric airborne
SAR system operative in the X- and L-band, developed by NICT and JAXA,
respectively, has conducted experimental
observations. A huge amount of high resolution data sets has been acquired with
this system. Since scattering matrix data provides with 9 independent
real-valued polarimetric scattering information as second-order statistics, it
has much more information than the data by single polarization radar. These
second-order statistics data can be used for various radar sensing applications
such as decomposition of scatterers, classification of terrain, retrieval of
some specific scatterers or physical features, environmental monitoring,
disaster surveillance, etc.
Decomposition of scattering mechanism
from objects is attractive issue for radar remote sensing. If the scattering
mechanism is well retrieved, it becomes possible to classify and identify
scatterers precisely. In this regard, a model-based four-component
decomposition method has been developed by [Yamaguchi et al., 2005a,b, 2006a].
This decomposition method was applied to monitor seasonal change of wetland
[Sato, R. et al., 2007], forest monitoring [Yamaguchi et al., 2006b],
earthquake [Yamaguchi et. al., 2006c], and Oyster farm [Lee et al., 2006].
Theoretical considerations were given to examine the polarimetric scattering
response by finite dihedral corner reflector [Sato, R. et al., 2005, Hayashi et
al., 2006], for interpretation of building wall to ground surface scattering.
[Yang el al., 2006] showed the stability for decomposition of Kennaugh matrix
with respect to noise for the case of sufficient number of samples.
Classification of terrain is also
attracting feature of polarimetric data. Correlation coefficients are used to
classify man-made structures as well as vegetation area in the HV basis by
Moriyama et al. [2005], and in the circular polarization basis by Yamamoto et
al. [2007] by combination use of radar cross section. Iribe and Sato [2007] used polarimetric
SAR data for estimation of target orientation in urban area. It is shown that
orientation angle is proportional to aspect angle of building blocks.
Estimating forest parameters using SAR
data is an important issue for studying the function of forests for carbon
cycle and global warming. High degree correlation was found between the
above-ground biomass of the coniferous forests and the order parameter of
K-distribution in the cross-polarization images acquired by the airborne Pi-SAR
L-band data, and an empirical regression model was developed to estimate forest
biomass [Wang et al., 2006, Ouchi et al., 2005]. This non-Gaussian texture
analysis is capable of estimating forest biomass beyond the saturation limit
imposed by the conventional techniques based on radar cross section. Comparison
of the model-based and ground-truth biomass yielded the accuracy of the model
of the order of 85% [Ouchi et al., 2006a]. Another approach for estimating
biomass is to seek tree height by polarimetric SAR interferometry using ESPRIT (Estimation
of Signal Parameters via Rotational Invariant Techniques) method [Yamada, H et
al., 2005]. By the location difference of scattering center, canopy and ground
scattering centers are retrieved, which in turn yields tree height of forest.
A fully polarimetric dual frequency
AIRSAR scene from a rice-growing area in
A compact, fully polarimetric and interferometric FM-CW SAR
system was developed at
B.
Subsurface Objects and Landmine Detection
Ground-penetrating radar (GPR) uses
radio-wave to image the subsurface. Various applications and effective
algorithms of GPR have been investigated for humanitarian demining [Feng and
Sato, 2004], velocity analysis in inverse scattering [Zhou et al., 2005],
estimation of oil-contaminated soil distribution [Qi and Sato, 2005],
estimation of accurate buried position [Takahashi and Sato, 2006], and
classification of buried targets from a single GPR trace that was applied to
landmine detection [Savelyev, et al., 2007]. Qi and Sato [2007] used GPR to
monitor the dynamic movement of ground water table, and proposed a technique to
estimate hydraulic parameters.
Borehole radars is a method to image the
subsurface with an antenna put into a borehole that is drilled around the
target area. It can estimate the hydraulic characteristic of subsurface
fractures [Liu and Sato, 2005] and to evaluate hard rock structure in large
scale with radar and DC resistivity tomography techniques [Yi, et al., 2005].
Zhao and Sato [2006, 2007] showed that radar polarimetry approach was effective
in characterization of subsurface fractures by a borehole radar. Zhou, et al.
[2007] proposed an inversion algorithm which include radiation characteristics
of antennas and applied it to field measured data of a borehole radar. A new
directional borehole radar system was introduced [Sato and Takayama, 2007] and
a new algorithm for direction finding system was proposed [Takayama and Sato,
2007].
Sato, et al. [2005] summarize research activities for
humanitarian demining carried out at Tohoku University, including a few test
evaluation in mine affected courtiers such as Afghanistan.
C.
Others
Microwave emissions due to hypervelocity
impacts and their dependence on the target material are investigated. The
signals were composed of two kinds of waveform: intermittent sharp pulses and
white noise. The energy of the pulses was greater for conductors than for
insulators. It was hypothesized that the microwaves were emitted from a
discharge along a micro-crack in the target [Maki, et al., 2005]. Experimental
study of microwave emissions due to rock fractures is made. When samples of
rocks were pressed by uniaxial loading to fracture, the signals were detected
at 22 GHz, 2 GHz and 300 MHz and 0.3- 300kHz. The pulse signals were detected
after the decrease of the load, and even after the stop of the fracture process.
A hypothesis of the generation mechanisms of the microwaves is considered on
the basis of the electrical charge accumulation due to piezoelectricity or
triboelectricity and the resultant discharges in micro-cracks [Maki, et al.,
2006]. In order to clarify the mechanism of charging and discharging across the
micro-crack, experiments are carried out and its results suggest that electrons
are excited both thermally and by transition from a crystalline state to an
atomic state [Ohnishi, et al., 2007]. Takano, et al. [2007] discuss the
experimental setup, the results, and the applicability of the phenomena to
geophysical explorations including material characteristics, change of the
underground structure, and earthquake detection. Waveforms of the microwave
emission are compared to the simulated one on the basis of a micro-crack model,
and its frequency spectra are compared to the calculated one. The results show
the microwave emission is not noise but a sequence of independent pulses [
Anomalies of the
electromagnetic field or the ionosphere have been observed before earthquakes,
in the frequency ranges up to VHF (3- 30 MHz). Microwave emission on the
occasion of earthquakes is also suggested, but it has not been measured. The
level of microwave (S-band, 2GHz) that is used for the communication between
tracking stations and earth-orbiting satellites is extracted corresponding to
major earthquakes broken out all over the world from 1986 to 2004. As a result,
some anomalies have been found out [Maeda. et al., 2006].
As space debris are increasing in orbits
around the Earth, its measurement is a key issue for the investigation and
monitoring of space environment. A bistatic radar which is composed of
transmitter and receiver stations is proposed for the debris measurement. The
received radio wave is processed on the basis of VLBI (Very Long Baseline
Interferometry) techniques. The system has significant advantages over
monostatic radar. A bistatic radar system was formed to verify the validity
experimentally [Yajima et al., 2007]. SELENE, SELenological and ENgineering
Explorer, launched in 2007, will execute four-way Doppler measurements and
differential VLBI observation to make global mapping of the lunar gravity
field, together with two small sub-satellites: Relay Satellite (Rstar) and VLBI
Radio Satellite (Vstar) [Iwata et al., 2005].
(M. Satake)
References
Abidin, W., K. Fujisaki and M. Tateiba [2006a], Study on the
propagation environment evaluation for the mobile satellite link using GPS, Electronic Proc. of PIERS 2006, Aug.
2006.
Abidin, W., K. Fujisaki, and M. Tateiba [2006b], Empirical
study on mobile satellite link using portable GPS receiver, Proc. JC-SAT 2006, pp.21-26, Oct. 2006.
Abidin, W., K. Fujisaki and M. Tateiba [2006c], GPS
feasibility in the study of the received land mobile satellite signal quality
due to an obstacle, Electronic Proc. of
ISAP 2006, Nov. 2006.
Abidin, W., K. Fujisaki, and M. Tateiba [2007a], Analysis of
mobile satellite signal performance in the presence of ground blockage: A GPS
approach, Proc. 25th AIAA International
Communication Satellite Systems Conference (ICSSC-2007), CD-ROM, Apr. 2007.
Abidin, W., K. Fujisaki, and M. Tateiba [2007b], GPS
receiver and mobile satellite signal performance for equatorial region:
Adachi, A., T. Kobayashi, and T. Kato [2004a], Dual wind
profiler observations of a line-shaped convective system in southern
Adachi, A., W. L. Clark, L. M. Hartten, K. S. Gage, and T.
Kobayashi [2004b], An observational study of a shallow gravity current
triggered by katabatic flow, Ann.
Geophys., vol. 22, pp. 3937-3950.
Adachi, A., T. Kobayashi, K. S. Gage, D. A. Carter, L. M.
Hartten, W. L. Clark, and M. Fukuda [2005], Evaluation of three-beam and
four-beam profiler wind measurement techniques using a five-beam wind profiler
and collocated meteorological tower, J. Atmos.
Oceanic Tech., vol. 22, pp. 1167-1180.
Akimoto, M. and K. Watanabe [2004], Study on rain
attenuation considering rainfall-intensity dependent spatial correlation
characteristics, IEEE Global
Telecommunications Conference 2004 (GLOBECOM 2004), vol. 5, pp.2864-2868.
Akimoto, M., T. Shimizu and M. Nakatsugawa [2006], Path loss
estimation of 2 GHz and 5 GHz band FWA within 20 km in rural area, Electronic Proc. of ISAP 2006, a56 r100.
Alexander, S. T. Tsuda, J.-I. Furumoto, T. Shimomai, T.
Kozu, and M. Kawashinia [2006a], A statistical overview of convection during
the first CPEA campaign, J. Meteor. Soc.
Alexander, S. and T. Tsuda [2006b] Measurements of vertical
eddy diffusivity across the tropopause using radio acoustic sounding system
(RASS), Geophys. Res. Lett., 34,
L06803, doi:10.1029/2006GL028753.
Alexander, S., T. Tsuda and J. Furumoto [2007] Effects of
atmospheric stability on wave and energy propagation in the troposphere, J. Ocean. Atmos. Tech., 24, pp. 602-615.
Aoyama, K., M. Ikarashi, J. Nakamura, Y. Yamaguchi, and H.
Yamada [2007a], Polarimetric observation of trees in the X and Ku band by FM-CW
SAR system, Electronic Proc. of PIERS
2007,
Aoyama, K., M. Ikarashi, J. Nakamura, Y. Yamaguchi, and H.
Yamada [2007b], Development of the fully polarimetric FM-CW SAR and the
coherent decomposition of target, Electronic
Proc. of ISAP 2007, Niigata.
Awaka, J., N. Takahashi, T. Iguchi [2006], Modeling of
bright band having a smooth connection to snowfall for observation of rain from
space, Electronic Proc. of ISAP2006,
Singapore, a113_r47.
Bringi, V. N., M. Thurai, K. Nakagawa, G. J. Huang, T.
Kobayashi, A. Adachi, H. Hanado and S. Sekizawa [2006], Rainfall estimation
from C-band polarimetric radar in Okinawa, Japan: Comparison with 2D-video
disdrometer and 400 MHz wind profiler, J.
Meteor. Soc.
Bui H. P., H. Nishimoto, T. Nishimura, Y. Ogawa and T.
Ohgane [2007a], Doppler spectrum and performance of E-SDM systems in indoor
time-varying MIMO channels, Proc. of IEEE
AP-S 2007, pp. 1361-1364, June 2007.
Bui H. P., H. Nishimoto, T. Nishimura, T. Ohgane and Y.
Ogawa [2007b], Effects of mutual coupling and Doppler spectrum on the
performance of 2x2 MIMO E-SDM systems, Electronic
Proc. of ISAP 2007, pp. 1150-1153, Niigata.
Cherntanomwong P., J. Takada and H. Tsuji [2006], Reduction
of AOA estimation error due to perturbation in array response by spatial
smoothing preprocessing, Electronic Proc.
of ISAP 2006, Singapore.
Ching G. S., M. Ghoraishi, N. Lertsirisopon, J. Takada, I.
Sameda, H. Sakamoto and T. Imai [2007a], Analysis of DSRC service over-reach
inside an arched tunnel, IEEE Journal on
Selected Areas in Communications, vol. 25, no. 8, pp. 1517-1525, Oct. 2007.
Ching G. S., M. Ghoraishi, N. Lertsirisopon, J. Takada, I.
Sameda, R. Soma, H. Sakamoto, and T. Imai [2007b], Analysis and modeling of
DSRC service over-reach inside an arched transportation tunnel, Proc. of 14th World Congress on Intelligent
Transport Systems, Oct. 2007 (Beijing, China).
Davidson, G., K. Ouchi, G. Saito, N. Ishitsuka, K. Mohri and
S. Uratsuka [2006], Single look classification accuracy for polarimetric SAR, Int. J. Remote Sensing Lett., vol. 27,
nos. 21-22, pp. 5073-5080.
Dhaka, S. K., M.K. Yamamoto, Y. Shibagaki, H. Hashiguchi, M.
Yamamoto, and S. Fukao [2005], Convection-induced gravity waves observed by the
equatorial atmosphere radar (0.20 degrees S, 100.32 degrees E) in Indonesia, Geophys. Res. Lett., vol. 32, L14820.
Du, J., W. E. Ward, J. Oberheide, T. Nakamura, and T. Tsuda
[2007], Semidiurnal tides from the Extended Canadian Middle Atmosphere Model
(CMAM) and comparisons with TIMED Doppler Interferometer (TIDI) and meteor
radar observations, J. Atmos. Solar-Terr.
Phys., 69, 17-18, 2159-2202.
Feng, X., M. Sato [2004], Pre-stack migration applied to GPR
for landmine detection, Inverse problems,
Vol. 20, no. 6, pp. s99-s115.
Fondjo, F. F., K. Fujisaki, M. Tateiba and T. Matsuoka
[2006a], Derivation of a conditional distribution of fade-slope by the analysis
of absolute slope, Electronic Proc. of
PIERS 2006, Aug. 2006.
Fondjo, F. F., K. Fujisaki, and M. Tateiba [2006b], Level
crossing rate and average fade duration analysis in Ku-band satellite link, Proc. JC-SAT 2006, pp.57-60, Oct. 2006.
Fondjo, F. F., K. Fujisaki, and M. Tateiba [2006c], Fade
dynamics on earth-space paths at Ku-band in Fukuoka, Japan fade-slope
evaluation, comparison, and model, IEEE
Antennas and Wireless Propagation Letters, Vol.5, pp.80-83, Dec. 2006.
Franklin, F. F., K. Fujisaki and M. Tateiba 2004], Fade
slope analysis at 12 GHz in Kyushu Island, Japan, Proc. 2004 Korea-Japan Joint Conference on AP/EMC/EMT, pp.245-248,
Nov. 2004.
Franklin, F. F., K. Fujisaki, T. Matsuoka and M. Tateiba
[2005a], Improvement of fade slope model based on observed received signal
level at 12 GHz in Kyushu Island, Japan, Proc.
of ISAP2005, Vol.3, pp.1201-1204, Aug. 2005.
Franklin, F.F., K. Fujisaki, T. Matsuoka and M. Tateiba
[2005b], A study of the received signal level from satellite link for fade
slope modeling, Proc. of ISMOT-2005,
pp.211-214, Aug. 2005.
Franklin, F.F., K. Fujisaki, T. Matsuoka and M. Tateiba
[2005c], Fade dynamics on earth-space paths at Ku-band in Fukuoka, Japan
evaluation and comparison, Proc. of
JC-SAT2005, pp.49-52, Oct. 2005.
Franklin, F. F., K. Fujisaki and M. Tateiba [2005d], Fade
duration analysis on earth-space paths at Ku-band in Fukuoka, Japan, Electronics Letters, Vol.41, No.25,
pp.1362-1363, Dec. 2005.
Fukao, S. [2006], Coupling Processes in the Equatorial
Atmosphere (CPEA): A project overview, J.
Meteor. Soc.
Fukuda, K., K. Fujisaki, and M. Tateiba [2006], A computer
simulation of relative backscattering coefficients of sea surfaces in satellite
altimetry, IEICE Trans. Comm., Vol.
J89-B, No.7, pp. 1158-1164.
Fukushige M. and T. Imai, [2007], Analysis of polarization
diversity gain at base station in W-CDMA system, IEICE Trans. Commun., vol. E90-B, no. 9, pp. 2360-2367.
Furumoto, J., S. Iwai, H. Fujii, T. Tsuda, W. Xin, T. Koike [2005]
Estimation of humidity profiles with the L-Band boundary layer radar-RASS
measurements, J. Meteorol. Soc.
Furumoto, J., T. Tsuda, S, Iwai, T, Kozu [2006] Continuous
humidity monitoring in a tropical region with the equatirial atmosphere radar,
Furumoto, J., S. Imura, T. Tsuda, H. Seko, T. Tsuyuki, K.
Saito [2007] The variational assimilation method for the retrieval of humidity
profiles with the wind-profiling radar,
Ghoraishi M., J. Takada and T. Imai [2006a], A
peudo-geometrical channel model for dense urban line-of-sight street microcell,
Proc. of 17th International Symposium on
Personal, Indoor and Mobile Communications (PIMRC 2006), Sep. 2006
(Helsinki, Finland).
Ghoraishi M., J. Takada and T. Imai [2006b], Identification
of scattering objects in microcell urban mobile propagation channel, IEEE Trans. Antennas and Propagation,
vol. 54, no. 11, 3473-3480, Nov. 2006.
Gurubaran, S., R. Rajaram, T. Nakamura, T. Tsuda [2005], Interannual
variability of diurnal tide in the tropical mesopause region: A signature of
the El Nino-Southern Oscillation (ENSO), Geophys.
Res. Lett., 32, No. 13, L13805, 10.1029/2005GL022928.
Haneda K., J. Takada, T. Iwata, and Y. Wakinaka [2004],
Experimental Determination of Propagation Paths for the ETC System -- Equipment
Development and Field Test --, IEICE
Trans. Fundamentals, vol. E87-A, no. 11, pp. 3008-3015, Nov. 2004.
Haneda K., J. Takada and T. Kobayashi [2005a], Double
directional ultra wideband channel characterization in a line-of-sight home
environment, IEICE Trans. Fundamentals,
vol. E88-A, no. 9, pp. 2264-2271, Sept. 2005.
Haneda K., J. Takada, and T. Kobayashi [2005b], On the
cluster properties in UWB spatio-temporal residential measurements, COST 273,
12th Management Committee Meeting,
Haneda K., J. Takada and T. Kobayashi [2005c], Double
directional cluster properties investigated from a series of ultra wideband
propagation measurements in home environments, Proc. of XXVIIIth General Assembly of International Union of Radio
Science, F03.1,
Haneda K., J. Takada and T. Kobayashi [2006a], A parametric
UWB propagation channel estimation and its performance validation in an anechoic
chamber, IEEE Trans. Microwave Theory and
Techniques, vol. 54, no. 4, pp. 1802-1812, Apr. 2006.
Haneda K., J. Takada and T. Kobayashi [2006b], Cluster
properties investigated from a series of ultra wideband double directional
propagation measurements in home environments, IEEE Trans. Antennas and Propagation, vol. 54, no. 12, pp.
3778-3788, Dec. 2006.
Haneda K., J. Takada and T. Kobayashi [2007], Applicability
of UWB double directional propagation modeling for evaluating UWB transmission
performance, Proc. of 2007 Spring IEEE
Vehicular Technology Conference (VTC 2007 Spring), pp. 277-381, Apr. 2007
(Dubrin, Ireland).
Hara D. and T. Kobayashi [2005], Development of ultra
wideband electromagnetic phantom materials for antennas and propagation
studies, Proc. of The 13th Conference on Microwave Techniques,
Hayashi, K., R. Sato, Y. Yamaguchi, and H. Yamada [2006],
Polarimetric scattering analysis for a finite dihedral corner reflector, IEICE Trans. Commun., vol. E89-6, no. 1,
pp. 191-195.
Ikarashi, M., J. Nakamura, K. Aoyama, Y. Yamaguchi, and H.
Yamada [2006a], Laboratory measurements by a fully polarimetric FM-CW SAR in
the Ku-band, Electronic Proc. of PIERS
2006, Tokyo.
Ikarashi, M., J. Nakamura, K. Aoyama, Y. Yamaguchi, and H.
Yamada [2006b], A new FM-CW Pol-InSAR system for laboratory measurement, Electronic Proc. of PIERS 2006, Tokyo.
Imai T. and T. Taga [2006], Statistical scattering model in
urban propagation environment, IEEE
Trans. Veh. Technol., vol. 55, no. 4, pp. 1081-1093.
Imai T. [2006a], Novel ray-tracing acceleration technique
employing genetic algorithm for radio propagation prediction, IEICE Trans. B, vol. J89-B, no. 4, pp.
560-575. (in Japanese)
Imai T. [2006b], Novel ray-tracing acceleration technique
employing genetic algorithm for radio propagation prediction, Proc. of EuCAP2006, 2006.
Imaoka, K. et al. (2007), Five years of AMSR-E monitoring
and successive GCOM-W1/AMSR2 instrument, Proceedings
of the SPIE, Volume 6744, pp. 67440J.
Imura, S. J. Furumoto, T. Tsuda, T. Nakamura, A. Behrendt,
M. Onishi [2007] Estimation of humidity profiles by combining co-locating VHF
and UHF wind-profiling radar data, J.
Meteorol. Soc.
Inoue T. and Y. Karasawa [2005], Theoretical analysis on
level variation of wideband signals in Rayleigh fading environments, Trans. IEICE, vol. J88-B, no.9,
pp.1641-1649.
Iribe, K., M. Sato [2007], Analysis of polarization
orientation angle shifts by artificial structures, IEEE Trans. Geosci. Remote Sensing, Vol. 45, no. 11, pp. 3417-3425.
Irimajiri, Y., T. Manabe, S. Ochiai, H. Masuko, T. Yamagami,
Y. Saito, N. Izutsu, T. Kawasaki, M. Namiki, and I. Murata [2006], BSMILES -- A
balloon-borne superconducting submillimeter-wave limb-emission sounder for
stratospheric measurements, IEEE Geosci.
Remote Sensing Letters, vol. 3, pp. 88-92.
Ishida, M., O. Sasaki, M. Yoshikawa, N. Takahashi, K.
Hamaguchi and H.Ogawa [2005], A study on the prediction of rain fade duration
at millimeter wave, Proc. of ClimDiff
2005, Clim 52,
Ishihara, M. Y. Kato, T. Abo, K. Kobayashi, and Y. Izumikawa
[2006], Characteristics and performance of the operational wind profiler
network of the Japan Meteorological Agency, J.
Meteor. Soc.
Ito, C., and Y. Hosoya [2005], A proposal of a global
conversion method for different integration time rain rates by using M
distribution and regional climatic parameters, IEICE Trans. Commun., vol. J88-B, 5, pp.948-955 (in Japanese).
Ito, C., T. Ishikawa and Y. Hosoya [2006a], A study on
global prediction method for site diversity improvement using thunderstorm
ratio as a regional climatic parameter, The
first European Conference on Antennas and Propagation (EuCAP 2006),
Ito, C., and Y. Hosoya [2006b], A Proposal of modified
Lavergnat-Gole model for global conversion of different integration time rain
rates, Electronic Proc. of PIERS 2006,
Iwakiri N. and T. Kobayashi [2007], Joint TOA and AOA
estimation of UWB signal using time domain smoothing, Proc. of 2007 2nd International Symposium on Wireless Pervasive
Computing, San Juan, Puerto Rico.
Iwata, T., N. Kawano, T. Sasaki, T. Takano and Y. Takizawa
[2005], Development of SELENE small sub-satellites for lunar gravity
observation, IAC05, B5.2.01,
Kamio, K., K. Nishimura, and T. Sato [2004], Adaptive
sidelobe control for clutter rejection of atmospheric radars, Ann. Geophys., vol. 22, pp. 4005-4012.
Karasawa Y. [2005], MIMO propagation channel modeling, IEICE Trans. Commun., Special section on
Recent Progress in Antennas and Propagation Researches, vol.E88-B, no.5,
pp.1829-1842.
Karasawa, N. Gejoh, and T. Izumi [2005], Modeling and
analysis of OFDM transmission characteristics in Rayleigh fading environment in
which the delay profile exceeds the guard interval, IEICE Trans. Commun., vol.E88-B, no.7, pp.3020-3027.
Karasawa Y. [2007a], Statistical multipath propagation
modeling for broadband wireless systems, IEICE
Trans. Commun., vol.E90-B, no.3, pp.468-484.
Karasawa Y. [2007b], Innovative antennas and propagation
studies for MIMO systems, IEICE Trans.
Commun., vol.E90-B, no.9, pp.2194-2202.
Kasai, Y., J. Urban, C. Takahashi, S. Hoshino, K. Takahashi,
J. Inatani, M. Shiotani, and H. Masuko, [2006], Stratospheric ozone isotope
enrichment studied by submillimeter wave heterodyne radiometry: the observation
capabilities of SMILES, IEEE Trans.
Geosci. Remote Sensing, vol. 44, pp. 676-693.
Kimura Y., Y. Ebine, T. Imai [2006], Relationship between
vertical beam shaping and downlink capacity for W-CDMA base station antenna, Proc. of EuCAP2006, ESA SP-626, October
2006.
Kita, N.,
Kita, N.,
Kita N., W. Yamada and A. Sato [2006a], Path loss prediction
model for the over-rooftop propagation environment of microwave band in
suburban areas, Trans. IEICE Commun.,
vol. J89-B, no. 2, pp. 115-125 (in Japanese).
Kita N., W. Yamada and A. Sato [2006b], Path loss prediction
model for the over-rooftop propagation environment of microwave band in
suburban areas, Wiley, Electronics and
Communications in Japan, part I, vol. 90, no. 1, pp. 13-24.
Kita N., W. Yamada and A. Sato [2007], New method for
evaluating height gain for wireless access systems in microwave band, IEICE Trans. Commun., vol. E90-B, no.
10, pp. 2903-2914.
Kitao K. and S. Ichitsubo [2006], Path loss prediction
formula for urban and suburban areas for 4G systems, Proc. of IEEE 63rd Vehicular Technology Conference (VTC2006-Spring),
Melbourne, Australia, vol. 6, pp. 2911-2915.
Kitao K. and
Kobayashi, T., and A. Adachi [2005], Retrieval of arbitrarily
shaped raindrop size distributions from wind profiler measurements, J. Atmos. Oceanic Technol., vol. 22, pp.
433-442.
Kobayashi T. [2006a], Measurements and characterization of
ultra wideband propagation channels in a passenger-car compartment, IEICE Trans. Fundamentals, vol. E89-A,
no. 11, pp. 3089-3094.
Kobayashi T. [2006b], Measurements and characterization of
ultra wideband propagation channels in a passenger-car compartment, Proc. of The 9th International Symposium on
Spread Spectrum Techniques and Applications (ISSSTA 2006),
Kozono S., K. Nakajima, T. Soga and R. Wang [2007], A study
of narrow band multi-path channel phase difference characteristics on domain
with time and frequency axes, Proc. of
IEEE 65th VTC (Vehicular Technology Conference), pp.367-371, 2007.
Kozu, T., T. Shimomai, Zainul Akramin, Marzuki, Y.
Shibagaki, H. Hashiguchi [2005], Intraseasonal variation of raindrop size
distribution at Koto Tabang, West Sumatra, Indonesia, Geophys. Res. Letters, vol.32, L07803, doi:10.1029/2004GL022340.
Kozu, T., K.K. Reddy,
Kozu, T., T. Iguchi, Y. Takayabu, H. Hanado, and Y. Naofumi
[2006b], Estimation of raindrop size distribution parameter with TRMM
precipitation radar, Electronic Proc. of ISAP2006,
Landmann M., K. Sivasondhivat, J. Takada, I. Ida and R.
Thoma [2007], Polarisation behaviour of discrete multipath and diffuse
scattering in urban environments at 4.5GHz, EURASIP
Journal on Wireless Communications and Networking, vol. 2007, ID 57980,
2007.
Lee, S. K., S. H. Hong, S. W. Kim, J. S. Won, and Y.
Yamaguchi [2006], Polarimetric features of oyster farm observed by AIRSAR and
JERS-1, IEEE Trans. Geosci. Remote
Sensing, vol. 44, no. 10, pp. 2728-2735.
Liu, S., M. Sato, K. Takahashi [2004], Application of
borehole radar for subsurface physical measurement, Journal of Geophysical Engineering, Vol. 1, pp. 221-227.
Luce, H., G. Hassenpflug, M. Yamamoto, and S. Fukao [2006],
High-resolution vertical imaging of the troposphere and lower stratosphere
using the new MU radar system, Ann. Geophys.,
vol. 24, pp. 791-805.
Luce, H., G. Hassenpflug, M. Yamamoto, M. Crochet, and S.
Fukao [2007], Range-imaging observations of cumulus convection and
Kelvin-Helmholtz instabilities with the MU radar, Radio Sci., vol. 42, RS1005.
Maeda A. and T. Kobayashi [2005], Automated ellipticity
measurements of ultra wideband circular polarization antennas, Proc. of 2005 Antenna Measurement Techniques
Association, Newport, Rhode Island, pp. 437-441.
Maeda A. and T. Kobayashi [2007], An omnidirectional and
low-VSWR ultra wideband antenna for a frequency band of 6 to 40 GHz,
Ultra-Wideband, Short-Pulse Electromagnetics 8,
Maeda, T., T. Takano, K. Inoue and T. Kato [2006], Satellite
data analysis system for searching microwave emission associated with
earthquakes, IEEJ Trans. FM, vol.126,
pp. 227-232.
Maekawa, Y., T. Fujiwara, Y. Shibagaki, T. Sato, M.
Yamamoto, H. Hashiguchi, S. Fukao [2006a], Effects of tropical rainfall to the
Ku-band satellite communications links at the Equatorial Atmosphere Radar
Observatory, J. Meteor. Soc.
Maekawa, Y., S. Tsujino, Y. Shibagaki, T. Sato, M. Yamamoto,
H. Hashiguchi, S. Fukao [2006b], Rain attenuation characteristics of up and
down link radio waves of Ku-band satellite communications observed In Japan and
Indonesia, Electronic Proc. of PIERS 2006,
Tokyo, Japan, 2P2-12.
Maekawa, Y., T. Nakatani, Y. Shibagaki, T. Hatsuda [2007], A
study on site diversity techniques related to rain front motion using Ku-band
satellite signals, Electronic Proc. of
ISAP 2007, Niigata, Japan, 4D1-2.
Maki, K., E. Soma, T. Takano, A. Fujiwara, and A. Yamori
[2005], Dependence of microwave emissions from hypervelocity impacts on the
target material, Journal of Applied
Physics, vol.97, pp.104911/1-6.
Maki, K., Tadashi Takano, Eriko Soma, Kentaro Ishii, Shingo
Yoshida and Masao Nakatani [2006], An experimental study of microwave emission
from compression failure of rocks (in Japanese), J. of the Seismological Society of Japan, vol.58, pp.375-384.
Materum L., K. Sivasondhivat, J. Takada, I. Ida and Y. Oishi
[2007], Identification of relatively strong clusters in an NLOS scenario at a
small urban-macrocell mobile station, Electronic
Proc. of ISAP 2007, pp. 157-160,
Mori, S., J.-I. Hamada, M.D. Yamanaka, Y.-M. Kodama, M.
Kawashima, T. Shimomai, Y. Shibagaki, H. Hashiguchi, and T. Sribeviawati
[2006], Vertical wind characteristics in precipitating cloud systems over west
Moriyama, T., Y. Yamaguchi, S. Uratsuka, T. Umehara, H.
Maeno, M. Satake, A. Nadai, and K. Nakamura [2005], A study on polarimetric
correlation coefficient for feature extraction of polarimetric SAR data, IEICE Trans. Commun., vol. E88-6, no. 6,
pp. 2353-2361.
Murata, F., M.D. Yamanaka, H. Hashiguchi, S. Mori, M. Kudsy,
T. Sribimawati, B. Suhardi, and Emrizal [2006], Dry intrusions following eastward-propagating
synoptic-scale cloud systems over
Nakamura, J., M. Ikarashi, K. Aoyama, M. Mitanura, Y.
Yamaguchi, and H. Yamada [2007a], Classification of targets on road by fully
polarimetric and real-time FM-CW radar, Electronic
Proc. of PIERS 2007, Beijing.
Nakamura, J., K. Aoyama, M. Ikarashi, Y. Yamaguchi, and H.
Yamada [2007b], Fully polarimetric and interferometric FM-CW SAR system and its
preliminary measurement results, Electronic
Proc. of ISAP 2007,
Nakatani, T., Y. Maekawa, Y. Shibagaki, T. Hatsuda [2007],
Relationship between rain front motion and site diversity in Ku-band satellite
links, 25th International Communications
Satellite System Conference (ICSSC 2007), Seoul, Korea, AIAA-2007 -3173.
Nishi M., K. Honda and T. Yoshida [2005], UHF-TV band
shadowing characteristics affected by surrounding buildings, Proc. of ISAP 2005, Vol.1, pp.149-152,
2005.
Nishi M., S. Takahashi, and T. Yoshida [2006a], Indoor Human
Detection Systems using VHF-FM and UHF-TV Broadcasting Waves, Proc. of 2006 IEEE 17th International
Symposium on Personal Indoor and Mobile Radio Communications (PIMRC06),
TJ7-3, 2006.
Nishi M., T. Iwami,
Nishi M., T. Kawaguchi,
Nishi, N., M.K. Yamamoto, T. Shimomai, A. Hamada, and S.
Fukao [2007], Fine structure of vertical motion in the stratiform precipitation
region observed by a VHF Doppler radar installed in Sumatra, Indonesia, J. Appl. Meteor., vol. 46, pp. 522-537.
Nishimoto H., Y. Ogawa, T. Nishimura and T. Ohgane [2007],
MIMO E-SDM transmission performance in an actual indoor environment, IEICE Trans. Commun., vol. E90-B, no. 6,
pp. 1474-1486, June 2007.
Nishimura, K.,
Nishio, H., and Y. Maekawa [2006], Relationship between raindrop
size distribution and cross-polarization discrimination of the Ka-band
satellite communications link, Electronic
Proc. of PIERS 2006, Tokyo, Japan, 2P2-8
Ochiai, S., S. Tsujimaru, Y. Irimajiri, T. Manabe, and I.
Murata [2005], Stratospheric ozone and ClO measurement using balloon-borne
submillimeter limb sounder, IEEE Trans.
Geosci. Remote Sensing, vol. 43, no. 6, pp. 1258-1265.
Ogawa Y., H. Nishimoto, T. Nishimura and T. Ohgane [2005a],
Performance of 2x2 MIMO spatial multiplexing in indoor environments, Proc. of 2005 IEEE/ACES International
Conference on Wireless Communications and Applied Computational
Electromagnetics, pp. 486-489, April 2005.
Ogawa Y., H. Nishimoto, T. Nishimura and T. Ohgane [2005b],
Performance of MIMO space multiplexing in indoor line-of-sight environments, Proc. of VTC2005-Fall, vol. 4, pp.
2398-2402, Sept. 2005.
Oguchi, T., and T. Ihara [2006], Computer simulation of
enhanced backscattering from randomly distributed spherical scatterers at 30
GHz and comparison with measurement, Radio
Sci., vol. 41, RS6002, doi:10.1029/2006RS003468.
Ohnishi, H., S. Chiba, E. Soma, K. Ishii, K. Maki, T.
Takano, S. Hasegawa [2007], Study on microwave emission mechanisms on the basis
of hypervelocity impact experiments on various target plates, Journal of Applied Physics, vol. 101,
pp.124901-1-8.
Okano Y. and K. Cho [2006], Novel internal multi-antenna
configuration employing folded dipole elements for notebook PC, Proc. of EuCAP2006, 2006.
Okano Y. and K. Cho [2007a], Performance of multi-band multi-antenna
for mobile terminal employing folded inverted-L antennas, Electronic Proc. of ISAP 2007,
Okano Y. and K. Cho [2007b], Dependency of MIMO channel
capacity on XPR around mobile terminals for multi-band multi-antenna, Proc. of EuCAP2007, 2007.
Ono, K., Y. Nishimura, K. Nakama, K.Saito, S. Nomoto, and Y.
Karasawa [2005], An accurate estimation scheme of 1-min rainfall rate
statistics from 1-min rainfall data provided by the Meteorological Agency, Trans. IEICE Japan, vol. J88-B, no.8,
pp.1509-1518 (in Japanese)
Ono, K., and Y. Karasawa [2006a], 1-min rainfall rate
statistics in Japan obtained from 1-min rainfall data provided by the
Meteorological Agency and consideration on suitable distribution function model
for approximation, Trans. IEICE Japan,
vol. J89-B, no.3, pp.361-372 (in Japanese)
Ono, K., and Y. Karasawa [2006b], Consideration on
characteristics of spatial correlation coefficient of nth power of 1-minute
rainfall rate for accuracy improvement of rain attenuation probability estimation
method, Trans. IEICE Japan, vol.
J89-B, no.10, pp.1998-2011 (in Japanese)
Ono, K., and Y. Karasawa [2007], An accurate conversion
method of different integration time rainfall rate cdf using M-distribution
applicable to all over Japan, Trans.
IEICE Japan, vol. J90-B, no.3, pp.266-279 (in Japanese)
Onoda, H., M. Yamazaki, H. Yamada, and Y. Yamaguchi [2007],
Improvement of scattering model decomposition by esprit-based POL-INSAR, Electronic Proc. of ISAP 2007,
Ouchi, K., H. Wang, M. Watanabe, M. Shimada, T. Tadono, A.
Rosenqvist, S.A. Romshoo, M. Matsuoka, and S. Uratsuka [2005], On the forest
biomass and the order parameter of K-distribution in high-resolution airborne
polarimetric SAR data, Proc. IEICE
Workshop for Space, Aeronautical and Navigation Electronics, Daejeon,
Korea, pp. 5-9.
Ouchi, K. and H. Wang [2005a], Interlook cross-correlation
function of speckle in SAR images of sea surface processed with partially
overlapped subapertures, IEEE Trans.
Geosci. Remote Sensing, vol. 43, no. 4, pp. 695-701.
Ouchi, K. and H. Wang [2005b], On the cross-correlation of
speckle patterns in multilook SAR images of dynamic sea surfaces, Proc. IEICE Workshop for Space, Aeronautical
and Navigation Electronics, Daejeon, Korea, pp. 11-16.
Ouchi, K., H. Wang, M. Watanabe, M. Shimada [2006a],
Statistical analysis of K-distributed high-resolution polarimetric SAR image
fluctuations and applications to forest biomass estimation, Proc. 41st Remote Sensing Soc. Symp.
Ouchi, K., H. Wang, N. Ishitsuka, G. Saito, and K. Mohri
[2006b], On the Bragg scattering observed in L-band synthetic aperture radar
images of flooded rice fields, IEICE
Trans. Commun., vol. E89-B, no. 8, pp. 2218-2225.
Ouchi, K., H. Wang, N. Ishitsuka, G. Saito, and K. Mohri
[2006c], Analysis of the Bragg resonance scattering in L-band JERS-1 SAR and
Pi-SAR images of rice paddies, IEICE
Tech. Rep., vol. 106, no. 1, pp. 103-108.
Patra, A. K., T. Yokoyama, M. Yamamoto, T. Nakamura, T.
Tsuda, and S. Fukao [2007], Lower E region field-aligned irregularities studied
using the Equatorial Atmosphere Radar and meteor radar in Indonesia, J. Geophys. Res., 112, A01301,
doi:10.1029/2006JA011825.
Promwong S. and J. Takada [2005], Link budget evaluation
scheme for UWB transmission systems, Proc.
of 2005 International Workshop on UWB Technologies, FM4-1, Dec. 2005
(Yokosuka, Japan).
Qi L., M. Sato [2005], Application of electromagnetic
exploration techniques to oil contaminated soil, Buturi-Tansa, Vol. 58, no. 5, pp. 545-554.
Qi, L., M. Sato [2007] , Estimation of Hydraulic Property of
an Unconfined Aquifer by GPR, Sensing and
Imaging, Vol. 8, no. 2, pp. 83-99.
Ratnam, M. V., T. Tsuda, M. Shiotani, and M. Fujiwara
[2005]: New characteristics of the tropical tropopause revealed by CHAMP/GPS
measurements, SOLA, 1, pp. 185-188,
doi:10.2151/ sola.2005-048.
Ratnam, M. V., T. Tsuda, T. Kozu, and S. Mori [2006a],
Long-term behavior of the Kelvin waves revealed by CHAMP/GPS RO measurements
and their effects on the tropopause structure, Ann. Geophysicae, 24, pp. 1355-1366.
Ratnam, M. V., T. Tsuda, S. Mori, and T. Kozu [2006b],
Modulation of tropopause structure revealed by simultaneous radiosonde and
CHAMP GPS measurements, J. Meteor. Soc.
Renggono F., M., K. Yamamoto, H. Hashiguchi, S. Fukao, T.
Shimomai, M. Kawashima, and M. Kudsy [2006], Raindrop size distribution
observed with the Equatorial Atmosphere Radar (EAR) during the coupling
processes in the Equatorial Atmosphere (CPEA-I) observation campaign, Radio Sci., vol. 41, RS5002.
Rikuta Y., S. Fujita, F. Ohkubo, H. Hosoya, K. Hamaguchi, J.
Takada, and T. Kobayashi [2006], Indoor channel measurement of 26 GHz band UWB
communication system, Proc. of 2006
International Conference on Ultra-Wideband, Boston, U.S.A.
Sakurai, N., F. Murata, M. D. Yamanaka, S. Mori, J. -I.
Hamada, H. Hashiguchi, Y. I. Tauhid, T. Sribimawati, and B. Suhardi [2005],
Diurnal cycle of cloud system migration over sumatera island, J. Meteor. Soc.
Sato A., N. Kita, K. Itokawa, H. Watanabe and D. Mori
[2005], Frequency scaling for path loss estimation of 5-GHz band around 10-km
distance, URSI Commission F, Proc. of
ClimDiff 2005, ClimDiff. 28.
Sato, M., J. Fujiwara, X. Feng, Z. Zhou and T. Kobayashi
[2005], GPR development for landmine detection, Mulli-Tamsa (Korean SEG), Vol. 8, no. 4, pp. 270-280.
Sato, M., T. Takayama [2007], A novel directional borehole
radar system using optical electric field sensors, IEEE Trans. Geosci, Remote Sensing, Vol. 45, no. 8, pp. 2529-2535.
Sato, R, K. Hayashi, Y. Yamaguchi, and H. Yamada [2005],
Polarimetric scattering by a finite dihedral corner reflector, Electronic Proc. of ISAP2005, TC2-3,
Sato, R., Y. Yajima, Y. Yamaguchi, and H. Yamada [2007],
Investigation on seasonal water area change in
Savelyev, T. G., L. van Kempen, H. Sahli, J. Sachs, M. Sato
[2007], Investigation of Time-Frequency Features for GPR Landmine
Discrimination, IEEE Trans. Geosci.
Remote Sensing, Vol. 45, no. 1, pp. 118-129.
Seto, T.H., M.K. Yamamoto, H. Hashiguchi, and S. Fukao
[2004], Convective activities associated with intraseasonal variation over
Seto, T.H., M.K. Yamamoto, H. Hashiguchi, S. Fukao, M. Abo,
T. Kozu, and M. Kudsy [2006], Observational study on westerly wind burst over
Sumatra, Indonesia by the equatorial atmosphere radar - A case study during the
first CPEA campaign, J. Meteor. Soc.
Shibagaki, Y., T. Kozu, T. Shimomai, S. Mori, F. Murata, Y.
Fujiyoshi, H. Hashiguchi, and S. Fukao [2006a], Evolution of a super cloud
cluster and the associated wind fields observed over the Indonesian maritime
continent during the first CPEA campaign, J.
Meteor. Soc.
Shibagaki, Y., T. Shimomai, T. Kozu, S. Mori, Y. Fujiyoshi,
H. Hashiguchi, M. K. Yamamoto,
Shibata. S., C. Nagasawa, M. Abo, T. Maruyama, S. Saito, T.
Nakamura [2006], Lidar observations of sporadic Fe and Na layers in the
mesopause region over equator, J.
Meteorol. Soc.
Sivasondhivat K., J. Takada, M. Landmann, I. Ida and Y.
Oishi [2006], Street dependency propagation at MS based on urban macrocellular
measurement, Proc. of EuCAP 2006,
Nov. 2006 (Nice, France).
Sivasondhivat K., L. Materum, J. Takada, I. Ida and Y. Oishi
[2007], Experimental study and modeling of channel parameters at mobile station
in a site-specific urban macrocellular environment, Electronic Proc. of ISAP 2007, Niigata.
Sridharan., S., T. Tsuda, R.A. Vincent, T. Nakamura, and E.
Achmad [2006], A report on radar observations of 5-8-day waves in the
equatorial MLT region, J. Meteorol. Soc.
Sridharan, S., T. Tsuda, and S. Gurubaran [2007], Radar
observations of long-term variability of mesosphere and lower thermosphere
winds over Tirunelveli (8.7 deg N, 77.8 deg E), J. Geophys. Res., 112, D23105,
10.1029/2007JD008669.
Suzuki S, K. Shiokawa, Y. Otsuka, T. Ogawa, M. Kubota, M. Tsutsumi,
T. Nakamura, and D. C. Fritts [2007a], Gravity wave momentum flux in the upper
mesosphere derived from OH airglow imaging measurements, Earth Planet and Space, 59 (5), pp. 421-428.
Suzuki, S., K. Shiokawa, Y. Otsuka, T. Ogawa, K. Nakamura,
and T. Nakamura [2007b], A concentric gravity wave structure in the mesospheric
airglow images, J. Geophys. Res.,
112, D02102, doi:10.1029/2005JD006558.
Suzuki, T., C. Ito and Y. Hosoya [2005], A study of
effective space correlation parameter in Morita-Higuti prediction method for
satellite link site diversity improvement, IEICE
Trans. Commun., vol. J88-B, 5, pp.1001-1004. (in Japanese).
Suzuki Y. and T. Kobayashi [2005], Ultra wideband signal
propagation in desktop environments, IEICE
Trans. Fundamentals, vol. E88-A, no. 9, pp. 2272-2278.
Takahashi. H., C. M. Wrasse, D. Gobbi, T. Nakamura, K.
Shiokawa and L.M. Lima [2005], Airglow OH emission height inferred from the OH
temperature and meteor trail diffusion coefficient, Adv. Space Res., 35, pp. 1940-1944.
Takada J., F. Ohkubo, K. Haneda and T. Kobayashi [2005],
Ultra wideband double-directional channel measurements in an office
environment, Proc. of 2005 IEEE
International Conference on Ultra-Wideband,
Takahashi, K., M. Sato [2006], Parametric inversion
technique for location of cylindrical structures by cross-hole measurements, IEEE Trans. Geosci. Remote Sensing, Vol.
44, no. 11, pp. 3348-3355.
Takahashi, N. and R. Ohmoto [2004], An experimental study of
attenuation through vegetation for quasi-mm wave band fixed wireless access
system, Proc. of 2004 Asia-Pacific
Microwave Conference (APMC 2004), 268.
Takahashi, N., S. Ueno and R. Ohmoto [2005], Using space
diversity against attenuation through vegetation : A field study for quasi-mm wave
band fixed wireless access systems, Proc.
of 2005 Asia-Pacific Microwave Conference (APMC 2005), vol. 4, pp.
2325-2328..
Takahashi, N. and R. Ohmoto [2006], An experimental study of
space diversity effect against attenuation through vegetation for quasi-mm wave
band fixed wireless access system, Proc.
of the first European Conference on Antennas and Propagation (EuCAP2006),
347530.
Takahashi, N. and R. Ohmoto [2007], A beam forming technique
against reflected wave interference for fixed wireless access systems using
quasi-millimeter wave band, URSI
Commission F Proc. of Triennium Open Symposium (URSI-F 2007), PR. 2.4.
Takahashi S., T. Kobayashi, C-J. Ahn and K. Ishida [2006],
Effects of partial blocking of transmission array antenna on transmission performance
of MIMO, Proc. of First International
Conference on Communications and Electronics (HUT-ICCE 2006),
Takahashi S., T. Higashi, M. Nishi and T. Yoshida [2007],
Propagation characteristics of FM broadcasting waves in Niijima Island, Electronic Proc. of ISAP 2007,
pp.442-445, Niigata.
Takano, T., Ken-ichiro Maki, Eriko Soma, Shigeo Chiba,
Takashi Maeda, Akira Fujiwara and Shingo Yoshida [2007], Microwave emission
phenomena due to material destruction and its applications to geophysical
exploration, Butsuri-Tansa
(Geophysical Exploration), Vol.59, pp.561-573.
Takayama, T., M. Sato [2007] , A novel direction-finding
algorithm for directional borehole radar, IEEE
Trans. Geosci. Remote Sensing, Vol. 5, no. 8, pp. 2520-2528.
Tango T., H. Iwai, Y. Murakami, K. Sasaki and T. Horimatsu,
An analysis of propagation loss characteristics for inter-vehicle
communications in non line-of-sight intersections using ray-tracing technique, Electronic Proc. of ISAP 2007, Niigata.
Taniguchi T., S. Sha and Y. Karasawa [2005a], Statistical
distribution of eigenvalues of correlation matrices in i.i.d MIMO channels
under Rayleigh fading, Proc. of The 16th
Annual IEEE International Symposium on Personal Indoor and Mobile Radio
Communications (PIMRC '05), C02-03, Sep. 2005.
Taniguchi T.,
Taniguchi T., A. Maeda and T. Kobayashi [2006], Development
of an omnidirectional and low-VSWR ultra wideband antenna, International Journal on Wireless and Optical Communications, vol.
3, no. 2, pp. 145-157.
Taniguchi T., S. Sha, and Y. Karasawa [2006], Statistical distribution
of eigenvalues in MIMO channels, Proc. of
EuCAP2006,
Taniguchi T., S. Sha and Y. Karasawa [2007a], Largest
eigenvalue analysis in correlated MIMO rayleigh channels, Proc. of EuCAP2007,
Taniguchi T., M. Tsuruta and Y. Karasawa [2007b], Largest
eigenvalue distribution approximation in MIMO Nakagami–M fading channels, Proc.
of International Symposium on Advanced ICT(AICT2007), BUPT,
Taniguchi T.,
Taniguchi T., S. Sha, Y. Karasawa and M. Tsuruta [2007d],
Approximation of largest eigenvalue distribution in Rician MIMO channels, Proc. of IEEE 18th Inernational Symposium on
Personal Indoor, and Mobile Radio Communications (PIMRC2007),
Teshiba, M., H. Fujita, H. Hashiguchi, Y. Shibagaki, M.D.
Yamanaka, and S. Fukao [2005], Detailed structure within a tropical cyclone
"eye", Geophys. Res. Lett.,
vol. 32, L24805.
Trieu H. T. T., K. Haneda, J. Takada and K. Takizawa,
Verifying the effectiveness of the stored channel simulation in evaluating UWB
system performance, Electronic Proc. of
ISAP 2006,
Tsuchiya H., K. Haneda and J. Takada [2006], Investigation
of ultra-wideband propagation channel based on a cluster scheme, IEICE Trans. Fundamentals, vol. E89-A,
no.11, pp. 3095-3102, Nov. 2006.
Tsuda, T., M. V. Ratnam, T. Kozu, and
Tsujino, S., Y. Maekawa, Y. Shibagaki, T. Sato, M. Yamamoto,
H. Hashiguchi, S. Fukao [2007a], Rain attenuation characteristics of Ku-band
satellite links due to tropical convective clouds observed by X-band radar, Coupling Processes in the Equatorial Atmosphere
(CPEA) Symposium, Kyoto, Japan, 1P-20.
Tsujino, S., Y. Maekawa, Y. Shibagaki, T. Sato, M. Yamamoto,
H. Hashiguchi, S. Fukao [2007b], Rain attenuation characteristics of Ku-band
satellite links due to tropical convective clouds, 25th International Communications Satellite System Conference (ICSSC
2007), Seoul, Korea, AIAA-2007 -3174.
Tsuruta M. and Y. Karasawa [2006], Multi-keyhole model for
MIMO repeater system evaluation, Trans.
IEICE Japan, vol. J89-B no. 9, pp. 1746-1754.
Tsuruta M.CT. Taniguchi
and Y. Karasawa [2007]COn
statistical distribution of eigenvalues of channel correlation matrix in MIMO
multi-keyhole environment, IEICE Trans.
Commun., vol. E90-B no. 9, pp.2352-2359.
Uematsu, A., H. Hashiguchi, M. Teshiba, H. Tanaka, K.
Hirashima, and S. Fukao [2005a], Moving cellular structure of fog echoes
obtained with a millimeter-wave scanning Doppler radar at
Uematsu, A., M.K. Yamamoto, H. Hashiguchi, K. Hirashima, and
S. Fukao [2005b], Shear-induced roll structure of fog observed by a
millimeter-wave scanning Doppler radar, Geophys.
Res. Lett., vol. 32, L14824.
Uematsu, A., H. Hashiguchi, M.K. Yamamoto, S.K. Dhaka, and
S. Fukao S [2007], Influence of gravity waves on fog structure revealed by a millimeter-wave
scanning Doppler radar, J. Geophys. Res.,
vol. 112, D07207.
Vuokko L., P. Vainikainen and J. Takada [2005], Clusters
extracted from measured propagation channels in macrocellular environments, IEEE Trans. Antennas and Propagation,
vol. 53, no. 12, pp. 4089-4098, Dec. 2005.
Wada, E., H. Hashiguchi, M.K. Yamamoto, M. Teshiba, and S.
Fukao [2005], Simultaneous observations of cirrus clouds with a millimeter-wave
radar and the MU radar, J. Appl. Meteor.,
vol. 44, pp. 313-323.
Wang, H. and K. Ouchi [2005], Speckle cross-correlation in
multilook SAR images of dynamic sea surface processed with partially overlapped
sub-reference signals, Electronic Proc.
of IGARSS 2005,
Wang, W., K. Ouchi, M. Watanabe, M. Shimada, T. Tadono, A.
Rosenqvist, S.A. Romshoo, M. Matsuoka, T. Moriyama, and S. Uratsuka [2006], In
search of the statistical properties of high-resolution polarimetric SAR data
for the measurements of forest biomass beyond the RCS saturation limits, IEEE Geosci. Remote Sensing Lett., vol.
3, no. 4, pp. 495-499.
Xiong, T. J. Yang, W. Zhang, Y. Yamaguchi, and H. Hamada
[2007], Coherent enhancement for polarimetric SAR interferometry, Electronic Proc. of PIERS 2007, Beijing,
China.
Xu. X, Y. Yamaguchi, Y. Yajima, and H. Yamada [2007],
Preliminary result of ALOS/PALSAR fully polarimetric data and its comparison
with Pi-SAR data, Electronic Proc. of
ISAP 2007, Niigata.
Yajima, M., K. Tsuchikawa, T. Murakami, K. Katsumoto, T.
Takano [2007], Study of a bistatic radar system using VLBI technologies for
detecting space debris and the experimental verification of its validity, Earth, Moon, and Planets, vol.100, pp.
57-76.
Yamada W., N. Kita, K. Sakamoto [2005], A. Ando and T.
Takao, Effect of antenna directivity for outdoor mesh networking using MIMO
systems, Proc. of IEE 3G and BEYOND 2005,
pp. 483-487, Nov. 2005.
Yamada W., N Kita and A Ando [2007], Empirical formula of
effect on channel estimation error for adaptive MIMO-OFDM based WLAN system, Proc. of IEEE AP-S 2007, pp.3013-3016,
June, 2007.
Yamada, H., H. Okada, and Y. Yamaguchi [2005], Accuracy
improvement of ESPRIT-based polarimetric SAR interferometry for forest height
estimation, Electronic Proc. of IGARSS
2005,
Yamaguchi, Y., M. Ishido, T. Moriyama, and H. Yamada
[2005a], Four-component scattering model for polarimetric SAR image
decomposition, IEEE Trans. Geosci. Remote
Sensing, vol. 43, no. 8, pp. 1699-1706.
Yamaguchi, Y., M. Ishido, T. Moriyama, J. Yang, and H.
Yamada [2005b], Polarimetric SAR image decomposition for non-reflection
symmetry condition, Electronic Proc. of
ISAP 2005, TC2-5,
Yamaguchi, Y., Y. Yajima, and H. Yamada [2006a], A
four-component decomposition of POLSAR images based on the coherency matrix. IEEE Geoscience Remote Sensing Letters,
vol. 3, no. 3, pp. 292-296.
Yamaguchi, Y., Y. Yajima, and H. Yamada [2006b], Fully
polarimetric L- and X-band Pi-SAR observation of Tomakomai forested area,
Electronic Proc. of PIERS 2006,
Yamaguchi, Y., Y. Yajima, H. Yamada, S. Uratsuka, T.
Umehara, and T. Moriyama [2006c], X- and L-band Pi-SAR observation to Chuetsu
earthquake region, Japan, Electronic
Proc. of the 6th European Conference on Synthetic Aperture Radar (EUSAR 2006),
Dresden.
Yamaguchi, Y. [2007], Polarimetric SAR and its applications,
Chinese Journal of Radio Science,
vol. 22, no. 1, pp. 1-7, Feb.
Yamamoto, M. K., N. Nishi, T. Horinouchi, M. Niwano, and
Yamamoto, Y., Y. Yamaguchi, H. Yamada, R. Sato, and J. Yang
[2007], Classification of terrain using the correlation coefficient in the
circular polarization basis for X-band POLSAR data, Electronic Proc. of ISAP 2007, Niigata.
Yang, C-S., H-J. Han, J-K. Park, and K. Ouchi [2006a], Bar
charges and morphology in the Han River estuary using RADARSAT/SAR images, Proc. of Int. Pan Ocean Remote Sen. Conf.
Assoc., Busan, Korea.
Yang, C-S. and K. Ouchi [2006b], Automatic detection
approach of ship using RADARSAT-1 synthetic aperture radar, Electronic Proc. of PIERS 2006,
Yang, C-S. and K. Ouchi [2007], Ship detection approach
based on cross-correlation from ENVISAT ASAR AP data, Proc. Int. Symp. Remote Sensing,
Yang, J., Y. N. Peng, Y. Yamaguchi, and H. Yamada [2006], On
Huynen's decomposition of a Kennaugh matrix, IEEE Geoscience Remote Sensing Letters, vol. 3, no. 3, pp. 369-372.
Yasuda A., J. Awaka, and M. Kotaki [2007], Effects of
snowfall on wave propagation along a 7.7 km 18/26 GHz FWA link, Electronic Proc. of ISAP2007,
Yi, M-J., J. H. Kim, S. J. Cho, M. Sato [2005], Integrated
application of borehole radar reflection and resistivity tomography delineate
fractures at a granite quarry, Subsurface
Sensing Technologies and Applications, Vol. 6, no 1, pp. 89-100.
Yonezawa K., T. Maeyama, H. Iwai and M. Nohara [2005a], A
path loss characterization over 2 GHz by measurement in 800 MHz and 5 GHz
bands, Electronic Proc. of ISAP 2005,
pp.1109-1112.
Yonezawa K., H. Ishikawa and Y. Takeuchi [2005b], An
experimental study on path loss prediction formula in over-rooftops propagation
applicable over 2 GHz, Proc. of ClimDiff
2005, Diff.11.
Yonezawa K., H. Ishikawa and Y. Takeuchi [2006], Frequency
range extension of path loss prediction formula for over-rooftops propagation
in microwave band, Proc. of IEEE AP-S
2006, pp.4747-4750.
Yoshida T., M. Nishi, S. Takahashi, M. Kobayashi and A.
Kaneda [2006], "Observation of Co-seismic Electromagnetic Waves in VHF
Band Associated with Earthquakes, Proc.
of IEEE AP-S 2006, pp.4671-4673, 2006.
Yoshida T., S. Takahashi and M. Nishi [2007], Propagation
characteristics of FM broadcasting waves at the Mid Niigata Prefecture
earthquake, Electronic Proc. of ISAP 2007,
pp.446-449, Niigata.
Zhao, J-G., M. Sato [2006], Radar polarimetry analysis
applied to single-hole fully polarimetric borehole radar, IEEE Trans. Geosci. Remote Sensing, Vol. 44, no. 12, pp. 3547-3554.
Zhao, J-G., M. Sato [2007], Consistency analysis of
subsurface fracture characterization using different polarimetry techniques by
a borehole radar, IEEE Geoscience Remote
Sensing Letters, Vol. 4, no. 3, pp. 359-363.
Zhou J. and T. Kobayashi [2006b], Development of ultra wideband
electromagnetic phantoms for antennas and propagation studies, Proc of 2006 International Symposium on
Medical Information and Communications Technology,
Zhou, H., M. Sato, H. Liu [2005], Migration velocity
analysis and prestack migration of common-transmitter GPR data, IEEE Trans. Geosci. Remote Sensing, Vol.
43, no. 1, pp. 86-91.
Zhou, H., M. Sato, T. Takenaka, G. Li [2007], Reconstruction
from antenna-transformed radar data using a time-domain reconstruction method, IEEE Trans. Geosci. Remote Sensing, Vol.
45, no. 3, pp. 689-696.