To estimate the impact of electromagnetic disturbances on multi-carrier wireless systems, a method for converting an amplitude probability distribution (APD) of disturbance measured at a frequency to be valid for another frequency is presented. The conversion uses two parameters, the receiver noise power of the APD measuring equipment and a scale factor that can be estimated from a measured disturbance spectrum. The method is based on the assumption that the difference in measurement frequency affects only the relative scale of the probability distribution of band-limited disturbance amplitude, and is applicable to disturbances of practically importance such as 1) continuous or pulse-modulated wideband Gaussian noise, 2) disturbance with a much narrower bandwidth than receiver bandwidth B, and 3) repetitive short pulses with similar waveforms with an interval much longer than 1/B. The validity of the proposed method is examined by measurements of actual disturbances.

Theoretical and actual experimental investigations are made on a Loop Antenna System (LAS) consisting of N-gap loop antennas. A general formula for the LAS response to an external EM field is derived by using both the method of moments and techniques for transmission-line analysis. Numerical evaluation verifies that the LAS has favorable characteristics, such as invariable response within a wide frequency range. In addition, differences between the LAS method and the present open-field method in the results of measurement are evaluated. It should be noted that the LAS gives a much lower output for an electrical source than for a magnetic source, even if both sources produce the same value with the open-field method. It is concluded that conversion factors for the results from the LAS method to the open-field method strongly depend on the orientation of the source as well as its characteristics. Consequently, new conversion factors are proposed to obtain practical EMI measurements.

The measured values of electromagnetic disturbances should strongly correlate with degradation in the communication quality of digital wireless communication systems. The Amplitude Probability Distribution (APD) of a disturbance represents statistical information as applicable measurement readings that meet the above requirement. In this paper, correlations between APD measurements of disturbances and the bit error rate (BER) as a quality degradation index for victim systems are quantitatively investigated. Disturbance regulation by APD measurements is discussed from the viewpoint of protecting systems from disturbances. This investigation specifically considers the situation in which a repetition pulse disturbance impacts PHS and W-CDMA systems assumed as victims. The results confirm high correlations between the APD and BER not only experimentally but also theoretically under some conditions. A disturbance regulation criterion based on APD measurements is thus proposed for compliance testing of electronic appliances with the potential to act as disturbance noise sources.

A procedure for estimating radiated power of radio transmitter is proposed based on a statistical property of field intensity time variation distribution in a reverberation chamber. When random varying multipath waves produced by stirrers in a reverberation chamber are received together with a direct wave, the resulting mixed waves are regarded as a kind of multipath waves. Theoretical and experimental results are reported regarding a procedure for estimating radiated power from the 63.2% value of CDF (Cumulative Distribution Function) of an envelope of multipath waves.

Broadband antennas such as biconical antennas and log-periodic dipole antennas are generally used in automatic EMC measurements. However, these broadband antennas have not been used for accurate measurement because accurate specifications for them are lacking. Therefore, more accurate analysis is urgently required by the CISPR (International Special Committee on Radio Interference), to establish the specifications for broadband antennas for EMC measurements. In this paper, the AF of biconical antennas is calculated by using Moment Methods. The frequency characteristics and antenna height dependency of AF are presented. AF is also measured and compared to the data obtained by the calculations. Good agreement between the calculations and measurements is achieved, indicating the usefulness of our computation method. In addition, the effect of antenna separation distance and transmitting antenna height on AF is investigated. The calculated AF deviation from the reference value is nearly 0dB except for certain antenna arrangements. In these antenna arrangements, the field becomes null at the receiving antenna and widely varies in magnitude and phase around the null points. Therefore, the antenna is immersed in a non-uniform field, while the AF is defined on the assumption of a uniform field. Consequently, the erroneous AF will be derived from measurements around these null points and it will be greatly different from that obtained at other antenna heights. Thus, it is better to avoid these conditions during actual measurements. The effect of the ground plane on AF is also evaluated. AF is shown to be seriously affected by the ground plane especially at frequencies around 90MHz. It should be noted that AF deviation has crests corresponding to the null field at 300MHz. The obtained data will be useful in establishing specifications of biconical antennas for EMC measurements.

The electromagnetic field (EMF) distributions created inside a train carriage by the cellular radios of the passengers are analyzed and the impact their electromagnetic interference (EMI) on the implantable cardiac pacemakers is evaluated based upon the analysis results. Both computer simulations and experiments using 800 MHz and 2 GHz transmitters in an actual train carriage confirm that excessively high EMF, high enough to affect the normal functions of the pacemaker, does not occur inside the carriage provided the safe distance of 22 cm specified for pacemaker users is kept. A simplified histogram estimation method for electric field strength is newly developed to deal with the complicated EMF distributions. It allows the EMI risk to pacemakers by cellular radio transmission to be quantitatively evaluated. Methodologies are described first. Typical results of FDTD analysis and actual measurement data are then shown. Finally, considerations and conclusions are made.