Refocusing through building walls using synthetic aperture radar

In standard synthetic aperture radar (SAR) imaging the effect of the wall is not usually taken into account. For walls with high permittivity (and/or relatively large thickness) such as brick and poured concrete walls, this effect becomes important. In this paper, numerical and experimental study is performed to address the effect of the wall on the target images. The shift in the target position in the range direction is observed. An important influence of the wall, which is widening of the point spread functions along the cross range direction, is indicated. This effect significantly disturbs (defocuses) the target image. In order to capture this effect, transmissivity through building walls are measured and methods for refocusing are provided. The significance of refocusing methods is illustrated when multiple targets close to each other, are placed behind walls.