Contents I. Introduction
The increasing interest in the security of public spaces has led to a demand for sensor technology beyond traditional metal detectors and X-ray detectors. Millimeter wave (MMW) technology is a novel imaging technique to look through materials. Its application in concealed weapon detection (CWD) has been studied extensively for the past few years [1]. There are two approaches to MMW imaging for human security, which are passive systems that receive natural radiation from the target and active systems that receive scattered radiation.
