Osamu Fujiwara and Akira Sugiura

1. Conferences

1.1 Domestic Conferences and Meetings

On April 22, May 25 - 26, and June 9 - 10, the technical committee meetings on EMC organized by IEICE in cooperation with URSI-E were held in Tokyo, Awaji, and Sapporo, respectively. The numbers of presented papers were 9, 9 and 22, respectively.

1.2 International Conferences and Meetings

1. The first Pan-Pacific EMC Joint Meeting, organized by IEICE EMC Technical Committee, was held in Awaji on May 26 – 27. There were 12 regular presentations and 5 invited presentations.

2. The 6th International Symposium on Electromagnetic Compatibility and Electromagnetic Ecology was held in St. Petersburg, Russia, on June 21-24, 2005.

1.3 Future International Conferences and Meetings

1. The 2^nd International Conference on Electromagnetic Compatibility will be held in Phuket, Thailand, on July 27-29, 2005. The deadline of extended summary was March 15, 2005.

2. The 2005 IEEE International Symposium on Electromagnetic Compatibility will be held in Chicago, USA, on August 8 – 12, 2005.

3. The 2005 International Symposium on Microwave, Antenna, propagation and EMC Technologies for Wireless Communications will be held in Beijing, China, on August 8 – 12, 2005.

4. The EMC Europe Workshop, which focuses on the specific hot topic of the EMC in wireless systems, will be held in Rome, on September 19-21, 2005.

5. The 17^th International Zurich Symposium on Electromagnetic Compatibility will be held in Singapore, on February 28 – March 3, 2006.

6. The 7^th edition of EMC Symposium will be held in Barcelona on September 4-8, 2006.

2. Technical Trends

EMI antenna calibration

For EMI antenna calibration, the conventional standard antenna method has been investigated for antenna calibration using the vertical polarization. Theoretical and experimental studies were made to find preferable antenna arrangements and cable treatments. The validity of this method was proved by actual calibration of a biconical antenna made at an open area test site. The attainable uncertainty seems to be less than 0.3 dB for the frequency range 50 MHz to 250 MHz. (Prof. A. Sugiura)

Measurement method of EMI suppression ferrite core

Ferrite cores are usually attached to the mains/peripheral cables to reduce the common-mode disturbance currents flowing on the cables. However, there is no standard method and guideline for choosing cores suitable for individual equipment. Hence, theoretical and experimental studies have been made on the S-parameters of ferrite cores in the frequency range from 15 to 100 MHz. In addition, commercially available equipment, such as PC and microwave oven, was measured on the reflection coefficient seen from the mains cable port. From these studies, a promising method has been developed for predicting the suppression of EMI current provided by a ferrite core.

(Prof. A. Sugiura)

Interferences caused by microwave oven noises

Leakage of EM waves from microwave ovens may cause unwanted interference to wireless LAN systems in the 2.4-GHz band. Performance degradation of wireless systems (DS-SS WLAN and Bluetooth) caused by the oven noises was evaluated theoretically and experimentally. Numerical and experimental analyses were conducted to demonstrate the effectiveness of adaptive filtering techniques for reducing the microwave oven interference in DS-SS WLAN systems. (Prof. A. Sugiura)

Interference from PCs having spread spectrum clock systems

Electronic appliances such as personal computers (PCs) and peripheral devices radiate electromagnetic noise over a wide frequency range, which may produce interference with wireless systems. From experiments, it was found that the harmonics of the clock signal dominate the radiated noises from PCs above 1 GHz, and that the harmonics were frequency modulated due to the intentional sweep of the clock frequency (spread spectrum clocking: SSC). Thus, theoretical investigation was made on the effect of the spread spectrum clocking on the measured harmonic spectra. The impact of PC noises on an OFDM-based WLAN system was also evaluated with theoretical and numerical calculations. (Prof. A. Sugiura)

Electromagnetic radiation from electrostatic discharge (ESD)

The transitional electromagnetic field due to electrostatic discharge (ESD) of the electrification metal body causes strong electromagnetic interference to the ITE equipment. In this study, the magnetic field in the near field and the discharge current caused by contact discharge of an ESD gun to the ground were simulated by using the FDTD model. The validity of the simulation was verified from the magnetic field waveform measured with a magnetic field probe. (Prof. O. Fujiwara)

Discharge currents through hand-held metal piece from charged human body

Discharge currents through hand-held metal piece from a charged human body were measured with respect to approaching speeds and charge voltages. A circuit approach for calculating the discharge current has also been shown. As a result, we have found that in case of 300 V charge voltage, the current waveform is not affected by the metal piece approaching speed, while in case of 800 V charge voltage, the fast approach gives the higher current peak. These current waveforms can be predicted from a time invariant spark resistance and the measured frequency characteristics of a human body impedance seen from a hand-held metal piece. (Prof. O. Fujiwara)

Rise-time and Peak of the transient current due to air discharge

With two kinds of commercially available ESD-guns, we measured the transient current for the air discharge gun with arbitrary approaching speeds. As a result, we confirmed that a similar specific relationship holds between the rise-time and current peak for each ESD-gun despite the poor reproducibility of the current waveform, which is also supported by other researcher’s finding for the discharge of a charged metal spheroid. (Prof. O. Fujiwara)

Low impedance decoupling device for power supply line

A new decoupling device for power supply line, which was called LILC (Low Impedance Line Component) has been developed. This device uses conductive polymer, and this influences the decoupling performance. The study shows that the performance can be improved to design the conductivity appropriately. (Prof. N. Kuwabara)

Calibration method of capacitive voltage prove

Capacitive voltage prove (CVP) has been standardized by CISPR for the probe measuring the disturbances on the cable without contact. However, the calibration, which needed to contact a probe to the conductor of the cable, should be carried out before the measurement because the sensitivity changes by the structure of the cable. The new method, which used two CVPs, was developed to eliminate the need of the contact at the calibration. This method supplies the signal to the cable via one of the CVP and measure the electrostatic induction voltage between the outer conductor and the inner conductor of the CVP with a high impedance probe. In the next, the induction voltages of both CVPs were measured with the high impedance probe. We can obtain the common-mode voltage on the cable from these measured values, the signal source level and its inner impedance, and the capacitances between outer conductor and the inner conductor of both CVPs. (Prof. N. Kuwabara)

Simulation of undesired noise form printed circuit board

Undesired electromagnetic radiation from microstrip line on PCB with attached feed cable was studied by the experiment and FDTD simulation. In order to understand the effect of the termination on EMI coupling path source that results from the nonzero impedance, EM radiations from PCBs with different termination conditions are discussed by experiment and numerical methods. As the characteristics of EM radiation, the frequency responses of common mode current, electric field near a PCB and far electric field were studied. Since the radiation is proportional to frequency, EM radiations for the “open” and “matched” cases therefore follow 40 dB/dec. The “short” case indicates 60 dB/dec. of typical CM radiation. Relatively low impedance load such as 51Ω was voltage-driven at lower frequencies. The easier interpretation for coupling-paths and -mechanisms should be the further studies to estimate the EM radiation. (Prof. H. Inoue)

Electromagnetic noises from information technology equipment (ITE)

When a wireless LAN terminal is put on near a personal computer (PC), the communication quality might deteriorate because of the electromagnetic noise from the PC. The measurement result of the magnetic-field distribution of the PC case on 2.4 and 5 GHz that are the frequency band of wireless LAN was shown. In the ITE equipment, it is a problem that not only electromagnetic interference to other electronic equipment but also the digital circuit and the wireless-communication circuit interfere each other in the own equipment. In this study, the throughput of a wireless communication was used as a measurement index of a slight malfunction, which is caused by the electromagnetic interference between the inside of the ITE equipment. As a result, the possibility of the use of the communication quality as the index of the noise immunity of the ITE equipment was shown. The information leaks can be caused by receiving the electromagnetic radiation from ITE equipment, because screen information and key-stroke information are included in the radiation. At the present time, the level of an electromagnetic radiation with impossible reproduction of screen information was derived in this study. (Dr. S. Ishigami)

Countermeasure of lightning malfunction

The effect of the connection grounding method was evaluated as countermeasure technology of a lightning malfunction in the co-location. As a result, the current of the lightning serge of the cable can be greatly decreased by using metal cable with sheath between boxes and the connection grounding wire. (Dr. S. Ishigami)

ULF EM environment at southern Boso Peninsula

The short-term variability of geoelectrical potential and geomagnetic fields was measured at Kiyosumi, Uchiura, and Fudago stations located in the southern part of Boso peninsula, which is one of the most seismically active areas in Japan. The analyses have shown the capability to discriminate the signal sources. Especially, direction finding analysis of time series data has shown to be effective in source separation. (Prof. M. Hayakawa)