General properties of electromagnetic scattering by inhomogeneous anisotropic composite obstacles of arbitrary shape

Abstract

General properties of plane-wave scattering by inhomogeneous anisotropic obstacles of arbitrary shape and of arbitrary number are presented on the basis of the reciprocity relations and the forward-scatter theorem. For the composite obstacles with symmetrical tensor characteristics, it is shown that interchange of the direction of incidence and that of observation keeps the bistatic scattering cross section unchanged on a condition, and that reversion of the incident direction gives the same extinction cross sections (or the same scattering cross sections in case of lossless obstacles) on the other conditions. For the composite obstacles with unsymmetrical tensor characteristics the following results are shown: Interchange of the direction of incidence and that of observation accompanied with transposition of all the tensor characteristics keeps the bistatic scattering cross section unchanged on a condition. Moreover, reversing the incident direction and transposing all the tensor characteristics, we have the same extinction cross sections on the other conditions. In case some of the obstacles are perfectly conducting, we have the same results as before. For the two-dimensional problems which can be decomposed into E wave and H wave, the above-mentioned results hold without condition.