sorry I do not have the expertise to answer this question.

Non-ideal focusing in through-the-wall radar imaging, when considering multipath ghosts, refers to the degradation in the ability to accurately pinpoint and image targets behind obstructions. This phenomenon arises due to the "interactions" of electromagnetic waves with the environment, including walls, furniture, and other objects, which can lead to strong reflections. These reflections can create additional, unwanted signal paths between the radar and the targets, known as multipath propagation. The result is the appearance of ghost targets in the radar images, which are artifacts that do not correspond to actual physical objects in the target scene. These ghosts can significantly degrade the quality of the imaging and the accuracy of target detection and localization.