Penetrating radar systems for urban operations – Annual report 2009

This annual report is an account of the activities carried out and the results produced thus far in the first year of the three-year Armed Forces' project Penetrating Radar Systems for Urban Operations. The project involves a further development of the competence and technique platform established by FOI through earlier efforts in the area of wall penetrating radar and the detection of weapons and explosives under clothing. The project is focused on the phenomenological and technical study, evaluation and development of methods, signal processing and system solutions for high-resolution microwave systems with penetrating capacity. The project participates together with the US, Canada, France, Norway, Turkey, and Sweden in the recently started NATO group "Advancing Sensing Through the Walls Technologies". The research should primarily be directed towards methods and techniques that reduce false alarms and increase the detection capability, and that feature extraction capacity is central in these. Through the participation, FOI gets important information of on-going research The project takes part in a bilateral co-operation with the Frech ONERA aiming at the investigation and development of methods and techniques for wall penetrating radar. Within the framework of this cooperation wall-penetrating measurements have been carried out of a moving person in a closed room. Work is in progress on the analysis of these measurements and an MTIbased detection method has been successfully tested. This method points to the possibility of automatic detection of various kinds of human movements, down to breathing. The various movements display different characteristics, which raises hopes of the possibility to establish what kind of activity is taking place behind the wall. Antenna solutions and signal processing methods for imaging penetrating radar systems are being evaluated in the project. A conclusion drawn is that electronically switched array antennas for 3D imaging can be shaped with consideration of the requirements on portable, light, and cheap radar systems with a low energy consumption. Furthermore, initial calculations have been made showing how the antenna pattern is influenced by the propagation of the radar wave through a homogeneous wall structure compared to one containing reinforcement bars. Continued work is directed towards studies of implementation of antenna elements, transmitters, receivers, wave-forms and signal processing. Furthermore, studies are performed concerning imaging algorithms and Doppler based movement detection. Experimental verification is being investigated in laboratory environment. An initiated study investigates the possibility to use polarimetric waveforms which improves detection and recognition performance with human targets. A survey of international work found few systematic studies having been made concerning the use of radar polarimetry in the seethrough application. The study suggests polarization choices that should be tested experimentally.