Zero On-Axis Backscattering of an Anisotropically Coated Shell of Revolution

摘要

A sufficient condition for eliminating the on axis backscattering of ananisotropic impedance coated shell of revolution has been deduced. The outside and inside normalized surface impedances Z+ and Z with which this sufficient condition can be satisfied have all been found. One exceptional situation is when the impedance matrices are equal and skew symmetric with their determinants equal to -1. All other cases require that the two matrices be symmetric, their determinants be unity, and the determinant of their difference be zero. The shell under consideration can be a closed one. For such a body of revolution only the conditions on Z+ need to apply, i.e., Z+ must be either symmetric or skew symmetric, with detZ+ = +1. This is an extension of Weston's result to anisotropically coated bodies. Results of this work make available a wide class of models which, must have zero on axis backscattering cross section. All general purpose numerical codes for computing the scattering cross sections of anisotropic impedance coated objects should be checked for their accuracy against a selected group of such models. Such comparisons should provide indications of an error bound of the particular algorithm.