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.