Co-array-based Synthetic Aperture Active Imaging at Millimetre Wave Frequencies

ABSTRACTImaging technique based on aperture synthesis scheme using sub-arrays and post data acquisition beam forming at the millimetre wave frequencies is investigated theoretically and experimentally. Technique has been extended for use in three-dimensional imaging and multiple target scenario. Simulation results verifying the proposed technique are presented. This approach can be used to construct three-dimensional images using separate transmitting and receiving arrays. A program based on this imaging technique has been written in MATLAB to simulate the target scene and to investigate reconstruction of the image theoretically and with the data collected experimentally. Experimental verification has been done using horn antennas as transmitting and receiving apertures having 10° beam width and 24 dB gain at 30 GHz. Precise positioning of transmitting and receiving antennas is one of the critical requirements at millimetre frequencies. A practical system designed to work on this technique, would necessarily require precise fabrication and positioning especially at higher millimetre wave bands as the whole process is phase sensitive. But, the preliminary results show that the method has good active imaging performance indicating potential applications of this technique in the future at higher millimetre wave frequencies.