Pulse broadening, polarimetric and angular memory effects of wave scattering from very rough surfaces

Understanding wave scattering from very rough surfaces has practical applications to many areas, including remote sensing, radar imaging, ocean acoustics, wireless communications, ultrasound imaging, surface optics and semiconductor physics. This dissertation presents theoretical and experimental studies of pulse broadening, polarization and angular memory effects of wave scattering from high-slope, randomly rough surfaces. Very few analytical or experimental results exist for these types of surfaces; however these surfaces give rise to depolarization and backscattering enhancement.; The theoretical analysis extends the scalar first- and second-order Kirchhoff approximations with shadowing corrections to a multi-frequency, multi-angle, electromagnetic theory for analyzing pulse broadening, angular memory effects and polarimetric effects of scattering from one- and two-dimensional lossy dielectric and conducting rough surfaces. This theory is valid for scattering from very rough, high-slope surfaces, which are defined as surfaces with r.m.s. height and correlation length on the order of a wavelength and r.m.s. slope close to unity. This is the region where conventional Kirchhoff approximations and perturbation theories are not applicable. The second-order Kirchhoff term is reduced to numerically manageable double integrals and includes the ladder and cyclic terms. The second-order Kirchhoff terms give the depolarization, and the cyclic term gives rise to the enhanced backscattering. This dissertation also includes millimeter-wave experimental studies for accurately characterized, lossy dielectric rough surfaces.; Analytical and experimental results are presented for the co- and cross-polarized scattering cross sections and for frequency correlations and angular correlations. Frequency correlations are the correlations of the scattered waves at two different frequencies and represent the coherence bandwidth of the scattered waves. The inverse Fourier transform of the frequency correlations illustrates the pulse broadening in time. The angular correlations represent the correlation of waves at different scattering angles for different incident angles and show the "memory effect," which refers to the strong correlation observed when the difference in the transverse wave numbers is the same for the incident and the scattered wave. The theoretical and experimental results are compared for a variety of surface characteristics, incident and scattering angles, showing good agreement. The results illustrate the effects of the rough surface characteristics, illumination size, incident polarization and incident pulse width on the scattered wave.