Apparatus and a method for scanning personnel for the purpose of detecting and identifying certain categories of materials/objects. The invention utilizes stacked-circuit-board tiled assemblies, including one circuit board which carries an array of transmission/reception scanning microwave elements, which elements, during a scanning operation are shifted toward and away successively from a person being scanned. This motion is carried out in a manner enabling detection of peak valley (high and low) values of standing wave reflections, if any, which exist between one of these elements and a region of a person being scanned by the invention. These peak and valley values can be employed, with respect to the magnitude difference between them, to enable "found material/objects" identification.