Generalized Wideband Harmonic Imaging of Nonlinearly Loaded Scatterers

Wideband electromagnetic sensing and imaging of nonlinearly loaded scatterers is considered. Harmonic scattering theory is first presented, and then a generalized near-field, direct imaging functional is proposed for free-space and near-ground target localization within the context of forward-looking radar standoff detection exploiting sequential single-tone excitation. The developed scattering and imaging analysis framework is illustrated for point-like and extended targets through numerical experiments performed with a hybrid method-of-moments solver, in conjunction with a harmonic balance approach and an asymptotic field propagation technique. The steady-state harmonic scattering responses are examined in the time, frequency, and image domains for scatterers in free-space and half-space environments, and accurate target localization is demonstrated in all cases for each harmonic order considered.