In this paper, the author discusses the error due to deformation of sample on permittivity measurement by standing-wave method on rectangular waveguide using Finite Difference Time Domain. The analytical model is considered the samples of four different deformed cases; (1) undeformed and no-loss sample, (2) undeformed and lossy sample, (3) deformed and no-loss sample, and (4) deformed and lossy sample.
As a result, it is confirmed that a deformation of the sample has strong influence on an accuracy of complex permittivity measurement. Specifically, the auther presents an interesting relation between the measurement error and the degree of sample deformation, including quantitative value of the error as a function of geometrical relation of the sample deformation with respect to the electric field distribution.

View full abstract

A simple method is proposed for broadly changing and improving the matching frequency characteristics of a coaxial waveguide terminator, using a Open-Hole Ferrite material.
In this paper, it is clarified that the matching frequency is changed from 0.8GHz to 5GHz by selecting the size of open-hole or the distance between the open holes in the same ferrite, for example. These characteristics have been investigated by the Spatial Network Method's analysis.

View full abstract

The backscattering radar cross section (RCS) of square trihedral corner reflector is derived as a function of incident direction, and it is studied about the RCS Characteristics including elevation angle θ, as the parameters of frequency, incident polarization and the reflector's length.
Comparing theoretical results with experiments, good agreement is seen for the both horizontal and slant polarization cases.
In this paper, the method of physical optics which assumes the induced current on the surface of scatterer 2 times of the incident magnetic field is applied to calculate the 3-dimensional analysis of RCS.

View full abstract

Induced output voltages of a transmission line by the transient near-field generated by a small gap discharge are calculated from the discharge current with the parameters of line length and the distance between the source and the line. The calculation is performed by using the coupling theory based on S-parameters which is applicable to microwave frequencies. The measured outputs agree well with the calculated ones.

View full abstract

This paper is concerned with the study of coupling of an external electromagnetic wave to a nonuniform transmission line (NTL) of finite-length suspended above a conducting ground plane. The excited NTL is approximated by a cascaded series of uniform transmision lines (UTLs) together with a suitable set of equivalent distributed sources along the line to account for the effect of the external sources. To confirm the validity of this theory, the numerical results are compared to those by the method of moment (MoM) and laboratory experiments, for a few typical NTL structures terminated by arbitrary loads. Comparison of this approach with the rigorous MoM solution shows that this simple circuit-theory-based method provides reliable results.

View full abstract

In the practical application of a microwave power transmission system, care should be taken in a radio environment, since a transmission power is much higher than usual communication channels. Although reradiation of higher harmonic waves from a rectenna is a problem, its characteristics are not fully understood yet. In this paper, propagating higher harmonic waves generated in and radiated from a dipole rectenna are measured and the result of this measurement is evaluated by semi-theoretical consideration. The result will be fundamental data to evaluate re-radiation characteristics of harmonics in microwave power transmission systems.

View full abstract

Airborne and shipborne radar, communication and the related radio wave systems with simultaneous transmission and reception system (STR) have limited spatial interval between the transmitting and the receiving antenna. Thus suppression of self-interference due to the strong transmitted signal is an important problem. We have made an engineering model of STR with an adaptive cancellation technique, and evaluated for three kinds of interferences: CW, pulse, wideband signals.

View full abstract

Abstract-If two transmission lines such as microstrip lines are set in the neighborhood, a coupling or crosstalk phenomenon may be generated between them. When the coupling level is low, the phenomenon can be considered as a coupling of external fields by one transmission line to the other transmission line; a set of non-homogeneous differential equations with regard to a line voltage and current holds approximately. The fields can be obtained by estimating vector potentials of currents on the line section and the terminals in terms of a terminal voltage and current of the line concerned. Thus, a solution to the equations can be obtained in expression of a four-port network. Estimation of the coupling between microstrip lines is made by applying the terminal conditions to the expression. To confirm the theory, the experiment has been conducted; the experimental results are in good agreement with the theory.

View full abstract

The complex antenna factor (CAF) of a dipole antennaa with a balun is evaluated by calibrating the S parameters of the balun and calculating the effective length of the antenna element in the frequency range of 600 MHz to 2 GHz. The result is compared with that of the conventional 3-antenna method. The obtained values of CAF by the two methods agree in their absolute values up to 1.2GHz, Concerning the phases of CAF, two results are close in the whole hand.

View full abstract

A wide-band electric field sensor is expected much for measuring impulse noise or evaluating EMC facilities. An electric field sensor using an optical modulator is suitable because it can operate over a wide frequency range and it does not disturb electric field because it does not have metallic materials.
This paper describes the method for improving the frequency bandwidth of an the electric field sensor by resistively loaded element. The r esonant phenomenon of the sensor element was controlled by loading resistance on the element. First, the frequency response of the sensor was numerically analyzed by the moment method based on the equivalent circuit of the sensor, and the optimum distribution of resistance was obtained by the analysis. Then a sensor with resistively loaded element was fabricated and it's frequency characteristics were measured, and the measured value agreed closely with the calculated value. The frequency bandwidth of the sensor was made two times as wide as that of the sensor with the same long metallic element.

View full abstract

This paper describes a time domain magnetic field measurement process for measuring magnetic fields near printed circuit boards (PCBs) with a loop probe. In carrying out measurements, the loop probe needs to be calibrated in the frequency domain. In this process, a microstrip line with a Teflon substrate serving as the standard magnetic field source is employed as a means of calibrating the probe. The standard magnetic field intensities of the line are calculated by an approximate equation obtained from Ampere's law to simplify the calibration. The sensor-factor of the probe obtained from this method agrees with that obtained through the use of a standard G-TEM cell in 2 dB at frequencies below 1GHz. The waveforms of magnetic fields near a PCB having a four-layer construction are measured using a 10mm diameter loop probe as the calibrated magnetic field sensor. The generation of magnetic field waveforms causing the radiated emission from the PCB is found to depend on the circuit operating conditions. It is clarified that the time domain magnetic field measurement process is an effective tool for analyzing the sources of emission radiated from PCBs, and for investigating the radiation mechanism.

View full abstract

Radar cross section measurement techniques in a relatively small anechoic chamber have been discussed in this paper. A proper configuration of measurement system and antenna/target setting is studied for securing a wide dynamic measurement range. Quasi-monostatic configuration is recommended here instead of monostatic one, and various comments are made for reducing isolation error and background noise, calibration techniques, and antenna setting. Measurement examples are shown for a conducting plate and parallel plane waveguide cavities. These results are then compared with those derived theoretically by geometrical theory of diffraction and Wiener-Hopf technique. Good agreements have been obtained between them, and validity of our measurement is confirmed.

View full abstract