Microwave aperture synthetic radiometer and the passive millimeter wave imager of Beihang University

Abstract

Summary form only given. The imaging principle, system configuration, primary results and the next work plan of the PMWIR-BHU (Passive Millimeter Wave Imaging Radar of BeiHang University) are presented. The imaging principle of the PMWIR-BHU is based on aperture synthesis technique and digital beam scanning technique, it synthesize the sparse distributed antennas with small aperture and larger Filed of View (FOV) in the pupil plane into a large equivalent aperture by interferometry, and adopts digital beam scanning technique to obtain high resolution images with large instantaneous FOV. The PMWIR-BHU consists of an antenna array, a coherence receiver array and a digital signal processor. The antenna array is a Y-shaped array with 8 elements in each arm, and each element antenna is a potter horn antenna. The receivers operate at 34.1GHz with two single band down-converters and analog IQ demodulations, the output IF is 10~100MHz. The digital signal processor is consists of three AD converters, a digital correlation unit and a signal process unit. Each AD converter has 16 channels, operates at 200MHz sample rate with 8 bits. The digital correlation unit adopts 1bit correlation technique which works real-time. The signal process unit is used to calibrate the raw measurement, and to inverse the passive millimeter wave image of the scene. At present, the PMWIR-BHU has been tested carefully, and a serial of imaging experiments are carrying out. The primary results are satisfied. In the next, our focus is on the accurate calibration and its application in security imaging.