Scattering Cross Sections of Impedance-Matched Bodies

Electromagnetic scattering from bodies with the surface impedance equal to the wave impedance of the surrounding medium shows a number of extremal features, including vanishing axial backscattering cross section in the case of bodies of revolution. This paper examines various scattering cross sections (mono- and bistatic, total scattering, absorption, and extinction) of electrically large arbitrarily shaped impedance-matched bodies, and it is shown that the backscattering cross section of arbitrarily shaped convex impedance-matched bodies vanishes in the optical limit. Furthermore, it is conjectured that considered as functions of the surface impedance, the mean total scattering cross section has a global minimum and the mean absorption cross section a global maximum when the body is illuminated by plane waves with random incidence direction and polarization.