For analyzing the transient electromagnetic fields caused by electrostatic discharge (ESD), a new ESD model is presented here. Numerical calculation is also given to explain the distinctive phenomenon being well-recognized in the ESD event.

The characteristics of an open-boundary Cherenkov laser for an electromagnetic wave with a continuous frequency spectrum are numerically analyzed. A given power spectral density for the input wave is found to get concentrated around the frequency where the spatial growth rate is maximum, as it grows along the electron beam. In addition, the frequency for the maximum growth rate is found to shift gradually to higher values. Furthermore, by gradually increasing the permittivity of the dielectric waveguide along it, we can always get the maximum power spectral density at the frequency where the spatial growth rate initially becomes maximum at the input.

Scattering characteristics of a stratified chiral slab, which is composed of dielectric chiral layers of different material properties and thicknesses, are extensively explored. Design considerations for optical filters are also presented for both the cases of normal and oblique incidence. In the analysis, the incident field is assumed to be a plane monochromatic wave of any arbitrary polarization. The transmitted and reflected electric fields are obtained by noting the fact that the electric field inside a chiral medium is expressed as a sum of the left- and right-circularly polarized plane waves of different phase velocities. Then one can describe the power densities and the Stokes parameters of the transmitted and reflected waves in terms of their field components. As is well known,the Stokes parameters characterize every possible state of polarization of a plane wave. Numerical examples are presented to show the effects of chirality on polarization conversion properties of the stratified chiral slab. The cross- and co-polarized powers and the Stokes parameters of the transmitted and reflected waves are computed for the incident wave of perpendicular polarization. The numerical results demonstrate novel depolarization properties of the slab with application to the design of efficient filters active at the optical region. It is seen from the results that the stratified chiral slab acts as a polarization-conversion transmission filter that passes only a cross-polarized component of the transmitted wave at some frequency band. Furthermore, the slab may be utilized as an antireflection filter for both the cross- and co-po1arized components of the reflected wave at the band region.

The authors developed new measuring system (Holographic Pattern Measuring System [HPMS]), which is composed of both techniques of holography and graphic image processing, was used to measure the vibrations of a printed circuit board (PCB) due to operation of a mounted electromagnetic relay on it. The clear vibration patterns were obtained. By using pattern analysis processor, quantitative vibration patterns of the PCB surface were observed. Both the vibration patterns and displacements were changed by edge fixing way of the PCB.

It is shown from a computer analysis that there exists a resonant mode of a surface wave which propagates along Goubau line, and that the attenuation of such a mode is very low. The approximate formula for obtaining the resonant frequency is also given.

An accurate numerical solution is presented for the electromagnetic scattering from a double strip grating, where the strip planes are each supported by a dielectric slab. This structure is a model of polarization diplexers. The direction of propagation and the polarization of the incident plane wave are arbitrary. We derive a set of singular integral equations and solve it by the moment method, where the Chebyshev polynomials are successfully used as the basis and the testing functions. By numerical computations we examine the dependence of the diplexing properties on grating parameters in detail. The cross-polarization characteristics at skew incidence are also referred. From these results we construct an algorithm for the design of polarization diplexers.

When we study time-domain electromagnetic fields, we frequently use the finite-difference time-domain (FD-TD) method. In this paper, we discuss errors of the FD-TD method and present the optimum mesh spacings in the FD-TD method when the three mesh spacings are different.

A coplanar-type TW electrode is analyzed for the use within a Ti:LiNbO3 optical modulator. The quasistatic analysis is developed based on the variational principle and the incremental inductance formula. The anisotropy of the LiNbO3, the effect of the SiO2 buffer layer, the overlaid conductor and the electrode thickness can be taken into consideration easily by using the extended spectral domain approach (ESDA) as the formulation procedure. It is shown numerically that the TW electrodes thickness, t, and the overlay spacing, p, are as dominant as the buffer layer thickness d, i.e., the microwave effective index and the product ΔfL is affected significantly by the electrodes thickness t and the overlay spacing, whereas the product VπL is insensitive. Therefore, the introduction of the overlaid conductor and the use of thicker electrodes can be utilized effectively to achieve higher values of the figure of merit Δf/Vπ.

This paper theoretically evaluates the external electro-optic (EO) sampling of high-speed electrical signals using poled polymers as materials for a proximity electric-field sensor. Based on the derivation of the half-wave voltage and the analysis of a static electric field coupled to the polymeric media placed over IC interconnections, invasiveness, voltage sensitivity, and spatial resolution have been discussed. The polymeric sensors have shown to be used in contact with the IC interconnections with negligibly small invasiveness, thus making polymeric sensors provide higher sensitivity and spatial resolution than inorganic crystals such as GaAs and KD*P.

In this paper, scattering waves by a strip grating with an anisotropic substrate for the incidence of inclined polarization are analyzed, and polarization characteristics of scatterd waves are calculated. For simplicity, the analysis is limitted to the case of normal incidence and a perfectly conducting strip grating is assumed.

With the use of a two-dimensional model, single laser beam trapping of particles is analyzed as the electromagnetic boundary-value problem. From the numerical results, it is found that the trapping mechanism for this system depends upon the surface field distribution of the object.

An efficient reconstruction algorithm for diffraction tomography based on the modified Newton-Kantorovich method is presented and numerically studies. With the Fréchet derivative obtained for the Helmholtz equation, one can derive an iterative formula for getting an object function, which is a function of refractive index of a scatterer. Setting an initial guess of the object function to zero, the pth estimate of the function is obtained by performing the inverse Fourier transform of its spectrum. Since the spectrum is bandlimited within a low-frequency band, the algorithm does not require usual regularization techniques to circumvent ill-posedness of the problem. For numerical calculation of the direct scattering problem, the moment method and the FFT-CG method are utilized. Computer simulations are made for lossless and homogeneous dielectric circular cylinders of various radii and refractive indices. In the iteration process of image reconstruction, the imaginary part of the object function is set to zero with a priori knowledge of the lossless scatterer. Then the convergence behavior of the algorithm remarkably gets improved. From the simulated results, it is seen that the algorithm provides high-quality reconstructed images even for cases where the first-order Born approximation breaks down. Furthermore, the results demonstrate fast convergence properties of the iterative procedure. In particular, we can successfully reconstruct the cylinder of radius 1 wavelength and refractive index that differs by 10% from the surrounding medium. The proposed algorithm is also effective for an object of larger radius.

This letter proposes an improvement of the equivalent source method in order to give an accurate solution for the scattering of an electromagnetic plane wave by a conducting cylinder with edges.

Analysis of the propagation of circularly symmetric fields is made using the finite-difference beam-propagation method. After testing the accuracy of this method, we analyze the guided-mode transmission of connected fibers whose core radii are different. The propagation behavior of the unguided-mode field generated at the junction is revealed using a transparent boundary condition.

An accurate numerical solution is presented for the electromagnetic scattering from infinite strip gratings attached to both sides of a dielectric slab. This structure is a model of polarization discriminating devices. The period of the strips is common to both planes, but the widths and the axes may be different. The direction of propagation and the polarization of an incident plane wave are arbitray. We derive a set of singular integral equations and solve it by the moment method, where the Chebyshev polynomials are successfully used as the basis and the testing functions. This method is accurate and effective owing to the incorporation of the edge condition and the decomposition of the kernel functions into the singular and the regular parts. Numerical calculations are carried out for the purpose of designing polarization discriminators, and it is shown that the band width is widened by decreasing the permittivity of the slab. The cross-polarization characteristics at skew incidence are also discussed.

This letter discusses the quality improvement of reconstructed images in diffraction tomography. An efficient iterative procedure based on the modified Newton-Kantorovich method and the Gerchberg-Papoulis algorithm is presented. The simulated results demonstrate the property of high-quality reconstruction even for cases where the first-order Born approximation fails.

A simple method is developed to analyze a bent waveguide, which is described in the cylindrical coordinate system. By means of this method based on the Galerkin method, the sampling spacing can be chosen arbitrarily and it is possible to treat narrow beams. In addition we introduce the absorber using the graded lossy material. As this lossy absorber can remove the radiation wave from the bend, so we can use the finite computational window. The lightwaves propagating in the uniform bend of the slab waveguide and of the nonlinear slab waveguide are demonstrated.

It is important to develop methods of measuring radiated electromagnetic interference level that will produce identical results at all measuring locations. We have considered a number of problems which prevent the achievement of identical results, and proposed some solutions. However, agreement of measurement values adequate for practical purposes has not been achieved. After our successive studies, we finally became aware that there is a causal relationship with changes in the line-to-ground impedance of the power supply. It is presumed that power cables of AC-powered devices operate as antenna elements that produce emission. Thus changes in the power line-to-ground impedance cause variations in the radiation efficiency to produce a different EMI level. We therefore made plans to measure the values of line-to-ground impedance at the AC power outlet for the frequency range of 100kHz to 500MHz at various locations where measurements are made of EMI from EUT (Equipment Under Test). The impedance varies greatly between 6ohms and 2 k-ohm, not only according to the frequency, but also according to the measurement location. In such cases, the EMI level shows a different value even with the same EUT, and it usually increases-especially for vertical polarization. We have developed a new type of LISN (Line Impedance Stabilization Network or Artificial Mains Network) to stabilize the power line-to-ground impedance to get consistent measurement conditions. The LISN consists of feed-through capacitors and an disk type RF resistor. The measurements confirm the consistency in the impedance value which is maintained at 50 ohms in the frequency range from 1MHz to 500MHz. Thus the newly developed LISN improves consistency of measurement values at all locations, while it was difficult to obtain good correlation before employing the LISN. We feel confident that incorporation of the method discussed here in the pertinent technical standards of EMI measurements, such as CISPR, would lead to a major improvement in getting consistent measurements values.

Anechoic chambers have been effectively used for microwave propagation, electromagnetic interference (EMI) and immunity testing. The electromagnetic compatibility (EMC) problem has recently become serious and many of these chambers have been constructed. The results of a questionnaire survey sent to anechoic chamber manufacturers are described that a total of 450 anechoic chambers have been constructed in Japan since 1964. Twenty years ago the purpose of the chambers was microwave propagation research, but more than 50 each year have recently being built for EMC/EMI and immunity testing. Their size has gradually been reduced by the use of absorbing materials such as ferrite with dielectric materials. The lowest frequency of most chambers is 30MHz for the 3 m method of site attenuation.

A new approach is proposed to evaluate total electromagnetic noise radiated from a printed circuit board (PCB), and a result of experimental verification is given. The purpose is to represent the total radiation noise by summing up noises from elemental sources on a PCB, such as signal traces or ICs. Each of the elemental noise is calculated by an a priori noise model for each component of a PCB. Parameters of each noise model should be determined experimentally. Radiation sources on a digital PCB were found to be not only signal traces between ICs, but also package-side loops each of which is composed of an IC and a decoupling capacitor. Radiation noises from these two kinds of sources were evaluated separately. Experimental PCBs, which are two-layer PCBs mounting a few high-speed CMOS (HC) ICs, were prepared and radiation power from them was measured. Each PCB has a ground plane on one side, which simulates an internal ground plane in a multilayer PCB, and signal traces on it have a configuration of a microstrip transmission line. Electromagnetic noise caused by a high-speed CMOS gate is radiated impulsively during transition time as short as about 10ns. No significant interference was found between the noises from separate traces because each of the noise is impulsive and rarely overlaps each other. It is concluded that the total radiated power is represented by a simple sum of radiations from each traces without any interference to be taken into account.