Multipath ghost elimination for through-wall radar imaging

In through-wall radar imaging, the multipath echoes caused by specular reflections at interior walls of an enclosed room will lead to multipath ghosts in the resulting image. The ghosts appear like the true targets and therefore tend to increase the number of false alarms. To solve this problem, a new ghost elimination method that removes multipath echoes from the raw radar data is proposed in this study. With a priori knowledge of the room, a concise multipath model is first developed, based on which the locations of the multipath echoes can be determined. Then, a cancellation process that consists of two steps is performed wherein the multipath echoes are cancelled in a specific order depending on the positions of the targets they correspond to. The major advantage of this method is that it can preserve the true targets while eliminating the ghosts even if the targets overlap with those ghosts. The effectiveness of the proposed method is validated by the processed imaging results using both the finite-difference time-domain-simulated data and the real experimental data.