A near-field back-projection algorithm for wall penetrating SAR

We are going to develop a handheld wall penetrating SAR (WPSAR) to investigate the small shallowly buried objects such as thin wires, cables and so on. The WPSAR will be working very close to the wall surface, and the objects of interest sometimes buried inside the induced near-filed region of the probe. As a result, the traditional far-field SAR imaging algorithm cannot be used. Thus, a useful near-field back-projection algorithm is investigated in this paper, which backprojects the probe´s aperture field into the wall, instead of backprojecting the echo signal along the wave propagation track as it is done in the traditional BP. A full wave simulation data given by CST is used to validate our algorithm. The result shows that the proposed near-field BP algorithm gives a correct imaging result while the traditional one fails.