The RCS Scaled-Measurement and Inversion Method for Metal Targets With Rough Surfaces Based on the Distribution of Surface Elements in the THz Band

In the terahertz (THz) band, due to the non-ignorable surface roughness, which is comparable to the wavelength, the scaled-radar cross section (RCS) measurement faces new challenges, which is referred to as the inconsistency with the electrodynamics similitude. As a solution, an RCS scaled-measurement and inversion method for rough metal objects is proposed based on the distribution of surface elements. With the consideration of the random fluctuation, the distribution of the facets was first studied, and a criterion was provided for quantitatively evaluating the difference in their distribution using Kullback–Leibler divergence (KL divergence). The core idea of our method is to construct an RCS estimation system of linear equations consisting of weight factors solved by relevant parameters of prior models. Both simulations and measurements on different scaled rough plates were conducted, demonstrating the effectiveness of the proposed method. Besides providing an effective solution to the scaled-RCS measurement for rough objects in the THz band, this work also introduces a new aspect in studying and estimating the scattering characteristics of rough surfaces.