MMW Sensor for Hidden Targets Detection and Warning Based on Reflection/Scattering Approach

An antenna sensor for millimeter wave (MMW) hidden target detection and warning applications is introduced. The sensor consists of three adjacent high gain microstrip/horn hybrid antenna elements. The central antenna acts as bi-static radar, while the two side antennas are used to receive the scattered back signals from a hidden object. The proposed antenna sensor has been employed in a detection/imaging system prototype based on time domain reflectometry (TDR). A very short pulse generated by a vector network analyzer is used to illuminate a three layers body model made from cotton, natural leather and reinforced papers. The model construction is chosen to emulate the presence of human body. Experimental scanning of a hidden metallic target has been conducted for three different orientations of the target. Compared to a single antenna sensor, the triple sensor shows a great enhancement in the detection ability and the constructed image resolution of a hidden target.