Improving the accuracy of measurement of bistatic scattering characteristics of material samples in various conf gurations

Abstract

The infl uence of diffraction effects at the edges of fl at samples of small (2–4 wavelengths of incident wave) sizes on the results of measurements of the refl ection coeffi cient of the sample material, a bistatic characteristic that depends on the frequency of radiation in a wide (10–85°) range of incidence angles is considered. To reduce the infl uence of diffraction effects, samples of various confi gurations have been developed, made of magnetodielectric with frequency dispersion of dielectric and magnetic permeability. The samples are a metal plate, on one side of which the material under study is applied, and the other surfaces of the plate are covered with radiation-absorbent material. The scattering characteristics of samples of the developed confi gurations are numerically calculated and experimentally measured on a bistatic facility in an anechoic chamber. The experimental results correspond with the calculated data. A noticeable reduction in the infl uence of diffraction effects on the refl ectivity values in a wide angular and frequency range has been shown. Using numerical methods in the FEKO software package, the infl uence of the sample confi guration on the methodical error in refl ectance measurements was studied. It is shown that this error can be reduced by using a substrate of an extended shape in the plane of incidence (samples of a hybrid confi guration). The results obtained can be used to measure the scattering characteristics of materials in free space.