“…Microwave images of both surface and interior features of non-conducting samples can be generated either by focusing the energy on the smallest possible spot and scanning either the target or the measurement probe (analogous to an ultrasonic C-scan), or by using coherent processing to form an image from multiple exposures of the entire target [2,3]. The latter approach, as implemented in an "Inverse-Synthetic-Aperture Radar" (ISAR) system has the significant advantage of being able to image complex, large and oddly shaped targets from a large stand-off distance (many meters).…”