The H-polarized diffraction by a wedge consisting of perfect conductor and lossless dielectric is investigated by employing the dual integral equations. Its physical optics diffraction coefficients are expressed in a finite series of cotangent functions weighted by the Fresnel reflection coefficients. A correction rule is extracted from the difference between the diffraction coefficients of the physical optics field and those of the exact solution to a perfectly conducting wedge. The angular period of the cotangent functions is changed to satisfy the edge condition at the tip of the wedge, and the poles of the cotangent functions are relocated to cancel out the incident field in the artificially complementary region. Numerical results assure that the presented correction is highly effective for reducing the error posed in the physical optics solution.

Scattering data from radar targets are analyzed in the time-frequency domain by using wavelet transform, and the scattering mechanisms are investigated. The wavelet transform used here is a powerful tool for the analysis of scattering data, because it can provide better insights into scattering mechanisms that are not immediately apparent in either the time or frequency domain. First, two types of wavelet transforms that are applied to the time domain data and to the frequency domain data are defined, and the multi-resolution characteristics of them are discussed. Next, the scattering data from a conducting cylinder, two parallel conducting cylinders, a parallel-plate waveguide cavity, and a rectangular cavity in the underground are analyzed by using these wavelet transforms to reveal the scattering mechanisms. In the resulting time-frequency displays, the scattering mechanisms including specular reflection, creeping wave, resonance, and dispersion are clearly observed and identified.

Scattering of a plane electromagnetic wave by a conducting wedge will be discussed. The former solution can not be applicable to all the transition regions when its parameter is constant. This study shows a new solution which consists of only one expression applicable to the shadow region, the illuminated region and the transition regions, and which has no parameter.

A detailed investigation of the electromagnetic field distributions inside waveguide circuits is useful for physical understanding, studies of electromagnetic coupling effects for EMC and EMI and for optimization of waveguide circuit designs. In this paper, we describe how to calculate and measure the two-dimensional electromagnetic field distributions inside waveguide-type planar circuits, making use of an analogy between H-plane waveguide- and trough-type surface-wave planar circuits. The measurement results are in good agreement with the results of the numerical analysis based on the normal mode expansion method.

A simple method based on the pattern integration method for measuring the power absorption by human model in the vicinity of antennas is proposed. Good agreement between the measured and the numerical results is obtained conforming the validity of the present measurement method. The equipment is useful in the EMC measurement and research of the antennas for the portable telephone.

A new numerical technique, termed the method of matrix-order reduction (MMOR), is developed for handling electromagnetic problems in this paper, in which the matrix equation resulted from a method-of-moments analysis is converted either to an eigenvalue equation or to another matrix equation with the matrix order in both cases being much reduced, and also, the accuracy of solution obtained by solving either of above equations is improved by means of a newly proposed generalized Jacobian iteration. As a result, this technique enjoys the advantages of less computational expenses and a relatively good solution accuracy as well. To testify this new technique, a number of wire antennas are examined and the calculated results are compared with those obtained by using the method of moments.

A wireless tag system has been designed and developed for maintaining and managing outdoor communication facilities. This system employs an infrared (IR) beam and an electromagnetic wave with a radio frequency (RF), and is constructed using IR-RF tags, an IR commander, and an RF receiver. The IR command radiation with strong directivity enables a maintenance operator to recognize a target facility, and the RF response without directivity enables a management system to obtain data from within a large circular area. Solar and secondary batteries are also adopted as the power module in the tag to allow easy maintenance at long intervals. IR signal communication is possible up to a distance of 9 m, and RF signal communication is possible within a circle with a radius of 9 m.

We propose an nn optical switch that is suitable for flexible and reliable optical access networks and for reconfigurable optical inter-module connections in large-scale processing systems. The switch consists of an intersecting waveguide matrix, matching oil, and microactuators. Switching is based on the movement of oil due to capillary pressure, which is controlled by the microactuator. The necessary switching conditions were calculated and the results showed that both the oil volume and the microactuator position must be controlled. A trial optical switch was fabricated to test the switching principle, and switching and self-holding were both confirmed. These results show the feasibility of a very small self-holding nn optical switch that uses a waveguide matrix and microactuators made by using microfabrication technologies.

This paper discusses the design of a small sensing device for EMI measurement which has equivalent characteristics to the absorbing clamp method, and reports the results on evaluation of the device. The device can be applied to the inspection apparatus for products such as power tools to examine conformance to EMI regulations of electromagnetic radiation spectrum. For reducing the scale of the EMI inspection apparatus, new matching circuit being replaced with the absorbing clamp method is adopted in the sensing device. Length of the sensing device is smaller than one twelfth of a wavelength of the measuring frequency in order to regard the sensing device as a concentrated constant circuit. The matching circuit is a resonant circuit which consists of a coaxial coupled transformer and a variable capacitor, and the transformer is a spiral copper tube in which a pair of AC power line wires passes. Resonant frequency of the circuit is tuned to the measuring frequency by adjusting the variable capacitor so that the circuit would terminate the power line by impedance zero. Thus interference current propagating along the power line from a product is absorbed, and observed by means of a VHF current probe which is settled in the matching circuit. A simple circuit for measurement of noise amplitude distribution (NAD) of interference current was developed as well as an equation to estimate quasi-peak value from the NAD. Result of measurement by the sensing device and proposed procedure confirmed good correlation with the standard absorbing clamp method, and deviation was within 3dB. Measurement time was reduced to 25 s per product, and the in-line EMI checker with new sensing device can be employed in a mass production line.

The coupling response of an external transient electromagnetic field to a transmission line is considered. An experiment has been conducted to verify the line equations for a transmission line excited externally by a transient near field. The model field is generated by a monopole antenna installed in the vicinity of the transmission line and driven by a step waveform. The waveform is analyzed into discrete spectrum components using a Fourier transform. The frequency-domain field components affecting the transmission line are estimated by the moment method, and then the induced frequency-domain voltage at the terminal load is converted into a time-domain voltage using an inverse Fourier transform. Comparison between the measured and the computed values provides verification of the line equations. The coupling mechanism is discussed from the experimental results. It seems equivalently that the transmission line picks up the field, generated at the feed point and the top point of the monopole antenna, at both terminal ends.

Over the past few years, many industrial processes have switched to electrical processes from conventional fossil fuel as a primary energy source, since electricity can be transmitted more economically than the transport of fossil fuels, as well as less pollution problems and labour- and spacesaving nature. For the environmental protections, ozone generation for water treatments, and decomposition of pollution gases such as SOx, NOx, COx, etc., by high pressure gas discharge processes become an important research subject. However, due to the early stage of development, the EMC problem is not yet well considered. In this review, we try to address the EMC problem in the various atmospheric pressure gas discharge processing techniques and identify future needs of research.

Surface discharge is widely used for industrial ozonizers and toxic gas treatments, and is noise source. In this paper, an experimental investigation from the point of view of electromagnetic compatibility (EMC) has been conducted to evaluate the noise characteristics of surface discharge combustion flue gas cleaning systems. Mechanisms of propagation, coupling and formation are proposed based on the experimental observations.

A new superresolution technique is proposed for high-resolution estimation of the scattering analysis. For complicated multipath propagation environment, it is not enough to estimate only the delay-times of the signals. Some other information should be required to identify the signal path. The proposed method can estimate the frequency characteristic of each signal in addition to its delay-time. One method called modified (Root) MUSIC algorithm is known as a technique that can treat both of the parameters (frequency characteristic and delay-time). However, the method is based on some approximations in the signal decorrelation, that sometimes make problems. Therefore, further modification should be needed to apply the method to the complicated scattering analysis. In this paper, we propose to apply a time-domain null filtering scheme to reduce some of the dominant signal components. It can be shown by a simple experiment that the new technique can enhance estimation accuracy of the frequency characteristic in the Root-MUSIC algorithm.

The problem of TM-mode scattering from the finite number of rectangular notches in a parallel plate waveguide is considered. The Fourier-transform is employed to obtain simultaneous equations and the simultaneous equations are solved to obtain an analytic solution in rapidly-convergent series. Numerical computations are performed to investigate the scattering behavior in terms of frequency and notch sizes. The presented theory is applicable to the analysis of scattering from the E-plane stubs in the rectangular waveguide.

New series expressing the radiation fields from both axial and circumferential slots on a circular conducting cylinder are derived. These new series converge rapidly even for near fields. This letter includes useful figures showing characteristics of near fields calculated numerically using the new series.

In this paper, electromagnetic scattering by infinite double two-dimensional periodic array of resistive upper and lower elements is considered. The electric field equations are solved by using the moment method in the spectral domain. Some numerical results are shown and frequency selective properties are discussed.

Research in radar polarimetry is hampered by shortcomings of the conventional formulation of polarimetric backscatter concepts. In particular the correct form of the Sinclair backscatter matrix under changes of polarization bases is derived from the antenna voltage (energy transfer) equation yielding the erroneous impression that radar polarimetry is a mongrel between scattering behavior and network performance. The present contribution restores logical consistency in a natural way by introducing the concept of an antilinear backscatter operator. This approach decouples scattering process and network performance, illuminates matrix analytical properties of the radar backscatter matrix and highlights characteristic states of polarization.

A folded short in parallel-plate waveguide is investigated using the Fourier transform and the mode-matching. A fast-converging series solution for scattering from the folded short is obtained and its characteristics are presented. Our solution for the E-plane short agrees well with measurements and is numerically more efficient than the existing moment-method solution. The presented scattering characteristics are useful for the design of the E- and H -plane shorts in rectangular waveguide.

The dielectric rod waveguides with corrugation consisting of nonintegral-ratio period waves are investigated numerically. The leakage characteristics of HE11-type wave in the waveguide is analyzed by applying Yasuura's method. The complex propagation constants and the far field patterns are presented. The radiation pattern of a fabricated waveguide with corrugation agrees well with the calculated value. The dependence of radiation characteristics on the corrugation form is discussed. It is shown that the leakage directions and the intensity of leaky waves are controlled independently one another. The radiation pattern can be synthesized by choosing the geometric parameters of the corrugation properly.

Standard Site Method (SSM) is theoretically analyzed using matrix representations to examine its validity and develop an improved method. The analysis reveals that the SSM yields an antenna factor specifically related to the effective load impedance presented by the cable and associated devices which are disconnected from the antenna during the SSM site attenuation measurements. Therefore, an additional conversion is required to determine the desired antenna factor under actual load conditions. It is also concluded that the SSM is not applicable to antennas having height-dependent antenna factors. In addition, the SSM correction factors are found to be theoretically inappropriate. Uncertainty of the antenna factor obtained using the SSM is discussed and the required antenna separation distance is investigated. To improve the existing SSM, it is proposed that both transmitting and receiving antennas are placed at the same height during the site attenuation measurements. Experiments exhibit the superiority of the improved method.