Generalized three-dimensional harmonic imaging of buried nonlinearly loaded scatterers

Wideband electromagnetic sensing and imaging of buried nonlinearly loaded scatterers is considered. Harmonic scattering theory is first presented, and then a generalized near-field, direct imaging functional is proposed for target localization within the context of downward-looking ground penetrating radar (GPR) detection exploiting sequential single-tone excitation. The developed scattering and sensing analysis framework is illustrated for a canonical scatterer through numerical simulations performed with a hybrid method-of-moments solver integrated with harmonic balance. Three-dimensional subsurface imaging is obtained with a moving linear transceiver array by re-focusing the steady-state harmonic responses received over a two-dimensional synthetic aperture.