Object detection method and apparatus employing polarized radiation

摘要

Methods and apparatus for detecting objects are disclosed. In one embodiment of the invention, a person entering a secured or "Safe Zone(TM)" is illuminated with low-power polarized radio waves. Differently polarized waves which are reflected back from the person are collected and measured. Persons carrying a concealed weapon such as a handgun are detected by calculating the difference of a pair of differences between levels of different polarized reflected energy. Alternative embodiments of the invention may be used to detect a wide variety of objects other than concealed firearms. The invention may be used for inventory control or to thwart shoplifting.