Experimental Anechoic Chamber Measurements of a Target near an Interface

The backscattered field of an illuminated sphere with diameter ∅ = 30.5 cm above a perfect conducting plate is measured in an anechoic chamber at different heights for a varying incidence angle φ in the range 5◦ to 75◦. A high frequency field λ ∅ is transmitted, so that two significant transitions from lit to shadow regions are given over the entire incidence angle range for the considered ray field. The polarimetric behavior of the measured scattering matrix [S] is investigated by using the common coherent and incoherent decomposition theorems used by the radar polarimetry scientific community. Close to the shadow boundaries the polarimetric behavior of the sphere significantly changes. Representing the different decomposition parameters used in radar polarimetry over the incidence angle range, the transition zones are related to local maxima or minima. Hence, the extreme values of the polarimetric parameters give information about the geometrical parameters e.g target size and its height above the plate.