Pulse broadening of the enhanced backscattering from rough surfaces

Recently, the authors presented a study of pulse scattering by rough surfaces based on the first order Kirchhoff approximation which is applicable to rough surfaces with rms slope less than 0.5 and correlation distance l⩾λ. However, there has been an increasing interest in enhanced backscattering from rough surfaces, and this requires inclusion of the second order Kirchhoff approximation with shadowing corrections. This paper presents a theory for the two-frequency mutual coherence function in this region and shows that the multiple scattering on the surface gives rise to an additional pulse tail in the direction of enhanced backscattering. The theory predicts pulse broadening approximately 20% greater than that caused by single scattering alone for a delta-function incident pulse and typical surface parameters. Analytical results are compared with Monte Carlo simulations and millimeter wave experiments for the one-dimensional rough surface with rms height of 1λ, and correlation distance of 1λ, showing good agreement