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A new type of the spectral domain method combined with the sampling theorem is applied to the rigorous analysis of the electromagnetic wave scattering by an infinite plane metallic grating in case of an oblique incidence and an arbitrary polarization. The accuracy and convergence of the present method are examined numerically from different angles, and it is found that the numerical results exhibit a good convergence even for a small truncation number. Some numerical examples are shown for the frequency characteristics of the reflected and transmitted powers, and the surface current distributions. Some versions in relation to the duality of the problem are also given.

The problem of an open microstrip line is anallzed by the spectral-domain method combined with the sampling theorem. In the spectral domain, the boundary conditions of zero tangential electric fields are expressed in terms of the convolution integral forms with a sampling function, and these relations are discretized by the method of moments with the spherical Bessel function as a weighting function. A well-chosen incorporation of the Weber-Schafheitlin integration formula yields good accuracy and saves a significant amount of time in numerical calculations. Numerical examples are shown for the effective dielectric constants and for the current distributions, both longitudinal and transverse, in comparison with the results obtained by various other methods.

This paper presents the result of a study on the error in propagation velocity introduced by the staircase approximation of a thin wire in the FDTD surge simulation. The FDTD method directly solves Maxwell's equations by discretizing the space of interest into cubic cells. Thus, it is suitable for solving very-fast surge phenomena which cannot be dealt with by conventional techniques based on the circuit theories. However, FDTD has a limitation that the shape of a conductive object must be modeled by a combination of sides of cells with forced zero electric fields. This indicates that a thin wire, one of the most important components in the surge simulation, results in a staircase approximation, if it is not parallel to any of the coordinate axes used for the discretization. A staircase approximation gives a slower propagation velocity due to the zigzag path which is longer than the actual length of the wire. For precise simulations, the error in propagation velocity has to be clarified quantitatively. In this paper, extensive simulations are carried out to obtain the velocity versus inclination characteristic, and it is deduced that the maximum error in propagation velocity is less than 14 %.

This paper investigates theoretically and experimentally the electromagnetic wave propagation in a two‐dimensional tunnel with a modified cross‐junction in connection with radio communications in tunnels, underground, urban areas with high‐rise buildings and others. Modal expansions and Fourier transform are used as an analytical method, and the surface impedance model is employed as a boundary condition on the tunnel walls. The results presented here can be applied to special tunnels such as the T‐type, modified T‐type, L‐type and step‐type. Experiments based on a microwave simulation are performed by using tunnels composed of concrete slabs. It is found that, concerning electric field intensity, experimental and theoretical results agree well.