Scattering and Imaging of Nonlinearly Loaded Antenna Structures in Half-Space and Complex-Room Environments

Report No. ARL-TR-7116
Authors: DaHan Liao and Traian Dogaru
Date/Pages: September 2014; 36 pages
Abstract: The electromagnetic scattering responses of nonlinearly loaded antenna structures excited by single-tone or multi-tone incident fields are considered in the frequency domain by employing a combination of the method-of-moments and a harmonic balance technique. Subsequently, standoff detection and localization of the scatterers in the presence of a half-space or within a complex room is demonstrated with a subspace imaging procedure by exploiting the steady-state, multistatic harmonic scattering responses collected over an aspect-limited aperture. For the half-space problem, the attenuation rates of the harmonic scattered fields as a function of sensing range are investigated; the Green's function vector in the imaging functional is derived efficiently with the application of second-order-accurate asymptotic propagation techniques; and nearfield imaging performance for single and multiple targets is also examined in the presence of noise and linear clutter. For the sensing-through-the-wall problem, the effectiveness of the imaging technique is analyzed with the assumption that the complex-room environment Green's function is not known a priori. This study is intended to provide an analysis and simulation framework needed to facilitate the development of a complementary nonlinear detection capability for an existing near-ground, forward-looking linear imaging radar system.
Distribution: Approved for public release
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Last Update / Reviewed: September 1, 2014