A Maximum Likelihood Extractor for Forward-looking Imaging of Multiple Unresolved Targets in Monopulse Radar

To improve azimuth resolution in forward-looking imaging, the amplitude comparison monopulse technique is used to measure the angle of a target in each range bin; thus energy can be projected to image pixels accurately. However, if there are multiple targets in the same range bin and beam, amplitude comparison monopulse fails to estimate the angle of each target correctly because of energy overlapped, which degrades image quality greatly. A maximum likelihood extractor is introduced to estimate the angles of these unresolved targets in forward-looking imaging. Simulation results show that the method can resolve up to five targets in a range bin and beam, so the image blurring can be removed effectively.