Retrieving Complex Permittivities From Remote Dual Co-Pol Radar Measurements

This article proposes an innovative method to retrieve the complex permittivities of the two faces composing dihedral structures. We use the HH and VV radar signals backscattered by a dihedral arrangement at two incidence angles to form two co-pol ratios. As the permittivity of a material does not depend on the incidence angle, we have two independent values. In addition, physical constraints on this permittivity (real part superior to 1, imaginary part negative or null) allow us to solve a polynomial equation derived from the Fresnel reflection coefficients. As we consider co-pol ratios, we alleviate the requirements for calibration for the intensity and the phase of the radar returns. Furthermore, we no longer need an a priori on the dimensions of the dihedral structure under observation. We tested this method experimentally, first in an anechoic chamber and then in real conditions. The results are promising.