Osamu Fujiwara and Akira Sugiura

1. Conferences

1.1 Domestic Conferences and Meetings

On December 9 - 10, 2004, and January 20 – 21, 2005, the technical committee meetings on EMC organized by IEICE in cooperation with URSI-E were held at Nagoya Institute of Technology, and NICT Okinawa, respectively. The numbers of presented papers were 15 and 30, respectively. Moreover, at the meeting on December 9, 2004, four invited speakers in EMC area from Asia countries gave their presentations on the latest research trends in their counties.

1.2 International Conferences and Meetings

1. 16th International Zurich Symposium on Electromagnetic Compatibility has been held in Zurich, Switzerland, form February 13 to 18, 2005. About 120 papers were presented at the symposium.

2. An International Workshop on Seismo Electromagnetics will be held in The University of Electro-Communications from March 15 to 17, 2005. Foreign participants are more than 50.

1.3 Future International Conferences and Meetings

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

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

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

4. 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. The deadline of paper submission is March 31, 2005.

5. Progress in Electromagnetics Research Symposium (PIERS 2005) will be held in Hangzhou, China, on August 22-26, 2005.

6. EMC Europe Workshop on Electromagnetic Compatibility of Wireless Systems will be held in Rome, Italy, on September 19 – 21, 2005. The deadline of paper submission is March 15, 2005.

2. Technical Trends

EMI antenna calibration

For EMI antenna calibration, the Antenna Impedance Method developed by us has been investigated in the frequency range from 30 MHz up to 10 GHz. It was found that this method could yield the free-space antenna factor with an uncertainty of about 0.3 dB or less.

A novel standard loop antenna using a hybrid junction has been proposed and investigated for EMI antenna calibration in the frequencies below 30 MHz. This antenna has a great advantage over the traditional standard loops in the respect that it is used as a receive antenna as well as a transmit antenna. (Prof. A. Sugiura)

Measurement method of EMI suppression ferrite core

A major source of the electromagnetic interference in the frequency range below 1000 MHz is disturbance currents flowing on the cables connected to an electronic device. Hence, in order to reduce the currents, ferrite cores are usually attached to enring the cables. However, there is no standard method for measuring the EMI suppression characteristics of the core. Hence, a measurement method has been studied and proposed for the insertion loss and the reflection coefficients of 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 using the 2.4-GHz band. To investigate the impact of oven noises on the wireless systems, a useful numerical model of the oven noise was developed. Performance degradation of wireless systems (DS-SS WLAN and Bluetooth) cause by the oven noises was evaluated theoretically and experimentally. The use of adaptive filters was proposed for reducing the microwave oven interference in DS-SS WLAN systems. (Prof. A. Sugiura)

Interference from PCs having dithered clock systems

Operating frequencies of the clock signals of personal computers (PCs) currently reach several GHz. Such devices radiate electromagnetic noise over a wide frequency range, which may cause interference with wireless systems. Measurements were carried out to investigate the characteristics of radiated PC noises in WLAN frequency bands (2.4 GHz and 5GHz). It was found that the harmonics of the base clock signal dominate the radiated noises from PCs, and that the harmonics were frequency modulated due to the intentional sweep (dithering) of the fundamental clock frequency. The impact of PC noises on an OFDM-based WLAN system was evaluated with numerical simulations. (Prof. A. Sugiura)

New design tool for printed circuit boards

Problems to control irradiative electromagnetic noise from digital electronic devices have been pursued. A concise equivalent circuit models have been developed which is useful as a powerful tool in designing printed circuit boards in terms of turn-around time and scale of computation. Practical speed was enhanced by 400 times than traditional methods. Accuracy of the models has been experimentally examined and objects of the models are extended to LSI levels as well as PCB. Results will help designers of electronic devices who are always expedited in developing their products.

Simulation of undesired noise form printed circuit board

Undesired electromagnetic radiation from microstrip line on PCB with attached feed cable is studied by the experiment and FDTD simulation. It was suggested that the differential mode current should be took into account for the undesired electromagnetic radiation at higher frequency. (Prof. H. Inoue)

Transmission characteristics on AC mains line

High speed power line communication (PLC) system has been developed to use for indoor communication system. The transmission characteristics and the influences to the electromagnetic environment should be studied because PLC system uses the AC mains line system which has not been designed to use for a high speed signal transmission. AC mains line with ground plane was presented by four-port networks to calculate both differential and common mode impedances. The radiated magnetic field was calculated from the common-mode current distribution. The results indicate that the deviation between calculated and measured value was improved to calculate the capacitance between conductors and between conductor and ground by using numerical method. (Prof. N. Kuwabara)

Investigation of disturbance for LF band

40kHz and 60 kHz are used to transmit the Japan Standard Time signal. The electric field strength of the 60 kHz transmitted signal and the disturbances in frequency range from 40kHz to 60 kHz were investigated. The results indicated that the field strength of the transmitted signal decreases in proportion with the increase of the distance, and there are many disturbance sources in this frequency range. (Prof. N. Kuwabara)

An Analytical Model for Current Injected Through Air Discharge of an ESD-Gun

An immunity testing method for electrostatic discharge (ESD) is being specified in IEC 61000-4-2, in which the contact discharge of an ESD-gun is being normally specified. Air discharge testing is known to be a severe immunity test compared to the contact discharge testing, while the discharge current injected is not well reproduced. Grasping the behavior of the current injected by the air discharge would be helpful in establishing the worst-case ESD immunity testing. We thus previously measured the discharge currents for air discharge testing onto the IEC recommended current transducer with a commercially available ESD-gun, and showed that there exists a specific relationship of Ip・trx/Vc=constant (x<1), between the rise time tr and current peak Ip. The current transducer, however, has frequency dependent transfer impedance, which should affect the measured current waveform. In this study, we proposed a method for estimating the discharge current from simultaneously measured magnetic fields with two magnetic probes. With this method, we estimated the discharge currents for air discharge testing onto a ground plane. As a result, we could confirm the existence of the above-mentioned relationship. (Prof. O. Fujiwara)

FDTD Simulation of Contact Discharge by an ESD-Gun

The electromagnetic noise caused by an electrostatic discharge (ESD) is a major source of malfunction to high-tech equipment. The ESD testing, therefore, is being specified in the IEC61000-4-2, which prescribes the current waveform from an ESD gun through a IEC recommended current detector (Pellegrini calibration target) . This IEC current waveform, however, does not always correspond to the one injected onto an actual device for ESD testing. In this paper, we simulated a contact discharge to ground plates using our previously developed FDTD model of an ESD gun. The induced voltages through a magnetic field probe were simulated when the discharge current was injected directly to the ground plate in contact with an ESD gun, whose results were confirmed with respect to the ground plate sizes experimentally. (Prof. O. Fujiwara)

TDR Analysis of EM Radiation from a Bend of Micro-Strip Line

Discontinuity such as a bend in a micro-strip line is known as one of major radiation sources. The total radiation from the micro-strip line is, however, being generally investigated because of the difficulties in identifying the radiation from some specific location. In this paper, paying attention to the feature of TDR (Time-Domain Reflectometry) measurement, we made an attempt to extract the radiation only from the bend in a micro-strip line. Such an approach is useful in understanding its radiation mechanism. As a result, we found that the larger the bend angle is, the larger the radiation power becomes. The radiation power achieved 3.5% at maximum when the bending angle was 90^o at the frequencies below 1 GHz. We also examined the validity of the TDR analysis in comparison with network analyzer measurement. We obtained the radiation power versus frequency from the measured scattering parameters, which exhibited a fair agreement with the TDR result. (Prof. O. Fujiwara)