A security system comprises a line array of antenna elements configured to transmit electromagnetic radiation and to receive scattered electromagnetic radiation scattered back from an object and an automatic movement element that automatically moves between at least two positions to perform a predetermined function. Said line array is mounted to said automatic movement element to transmit electromagnetic radiation to and receive scattered electromagnetic radiation from a screening area in front of and/or behind the automatic movement element. A controller controls said antenna elements to transmit electromagnetic radiation and to receive scattered electromagnetic radiation at a plurality of positions of the automatic movement element. A processor processes scattered electromagnetic radiation received at a plurality of positions of the automatic movement element and generates image information of the screening area using position information about the plurality of positions of the automatic movement element at which scattered electromagnetic radiation is received and used for processing. The automatic movement element is an automatic door that automatically opens and closes or an advertisement board that automatically changes between two or more advertisements. The automatic movement element is an automatic door that automatically opens and closes or an advertisement board that automatically changes between two or more advertisements.