Angular memory effect of millimeter-wave scattering from two-dimensional conducting random rough surfaces

An experimental study was conducted to investigate the angular memory effect of millimeter-wave scattering from two-dimensional conducting random rough surfaces. The surfaces under investigation were machine-fabricated with known Gaussian roughness statistics, and the copolarized and cross-polarized angular correlation functions (ACFs) of scattering amplitudes were measured. It was found that for the case of reference antenna positions located bistatically in a backward direction, the measured ACF exhibits broad response when single scattering dominates but two peaks when multiple scattering dominates. These observations are in good agreement with the second-order Kirchhoff approximation (KA2). Specifically, the observed broad and peak responses are analytically identified to be due to the first-order and second-order (ladder and cyclical) scattering components, respectively, in KA2.