Tokuya Itakura

Singular integral equation approach to plane wave diffraction by an infinite strip grating at oblique incidence

An accurate numerical solution of the plane wave diffraction by an infinite strip grating is presented, where the incident wave propagates in an arbitrary direction and is arbitrarily polarized. We derive a set of singular integral equations and solve it by the moment method, where the Chebyshev polynomials are chosen for the basis and the testing functions. The edge condition is incorporated in the expansion of the unknown functions in order to accelerate the convergence. A decomposition of the kernel into a singular and a regular part enables us to avoid the relative convergence phenomenon. Numerical results show the accuracy of the present method. Some numerical examples are presented for the polarization discrimination characteristics and surface current distributions.

Singular Integral Equation Approach to Electromagnetic Scattering from a Finite Periodic Array of Conducting Strips

An accurate numerical solution for the electromagnetic scattering from a periodic array of a finite number of conducting strips is presented, where the incident plane wave propagates in an arbitrary direction. Both TM and TE polarizations are treated. First, the boundary value problem is formulated into the solution of a set of Fredholm integral equations of the first kind with singular kernels. Then it is regularized to a set of the second kind equations which is numerically solved by the moment method. The present method is much more effective than the moment solution of the first kind equations. This is because the kernel functions of the resulting second kind equations are bounded and smooth, and because the edge condition is automatically taken into account in the course of the regularization. Some numerical examples are shown for the total scattering cross-sections, surface current distributions, and the far-zone scattered fields. The near zone fields are compared with the experimental data.

Scattering of an Arbitrary Plane Wave by an Infinite Strip Grating Loaded with a Pair of Dielectric Slabs

An accurate numerical solution for the electromagnetic scattering from an infinite strip grating is presented, where the strips are loaded with a symmetrical pair of dielectric slabs. The direction of propagation and the polarization of the incident plane wave are arbitrary. The boundary value problem is reduced to a solution of singular integral equations, which are discretized by an application of the moment method. Numerical computations are performed mainly for the purpose of designing polarization diplexers. Dependence of diplexing characteristics on grating parameters is examined in detail. Appearance of cross-polarized field at skew incidence is referred.