Impacts of Wall–Target Interaction on Matched Illumination Waveforms for TWRI

The impacts of wall-target interaction on matched illumination waveforms for through-the-wall radar imaging are examined via finite-difference time-domain simulation. Returns from various wall-target scenarios are considered as a function of the target-to-wall separation in order to examine the effectiveness of the so-called primary-wave target response in the matched illumination implementation. The primary-wave target response is shown to effectively maximize the signal-to-interference-and-noise ratio (SINR) in through-wall radar applications where the wall-target interaction is minor, and the primary-wave response closely resembles the full-wave target response, which contains all wall-target interactions. The ability of the primary-wave target response to maximize the SINR can be degraded by relatively minor errors in the wall-target transfer function caused by the incomplete wall-target physics inherent to the scheme. In such cases, the resulting matched illumination waveform spectrum is generally characterized by narrowband energy concentrated at suboptimal frequencies.