Identification of electromagnetic parameters of a wall and determination of radar signal level behind a wall

One of the challenges of using synthetic aperture radar (SAR) to detect a man behind a wall is determining the amount of signal attenuation introduced by the signal's propagation through the wall. This attenuation is difficult to determine because the thickness and the electromagnetic properties of the wall are normally not known a priori. We describe a procedure for estimating the relative permittivity, conductivity, and thickness of the wall that minimize the error between physics-based predicted values of wall return and the corresponding values of the SAR image. The accuracy of the prediction is a function of the resolution of the SAR image relative to the thickness of the wall-the SAR image must have sufficient resolution such that the locations of the front and rear surfaces of a uniform wall can be estimated from the SAR image. The signal level behind the wall, or equivalently the signal attenuation by the wall is then determined from the estimates of the thickness and electromagnetic parameters. We demonstrate the effectiveness of this identification procedure using data generated by XPATCH simulations of three different wall materials.