Detection of Unresolved Rayleigh Targets in Monopulse Radar With Two Angular Dimensions

For monopulse radar, unresolved targets occur if more than one target falls into the same resolution bin and beam. The detection of unresolved targets is necessary to prevent failure of target tracking in scenarios, such as formation targets, jamming, or small targets, masked by sidelobes of large objects. In this article, the detection of unresolved Rayleigh targets with two angular dimensions is studied. The joint probability density function (PDF) of the monopulse ratios in two angular dimensions is derived. Based on this PDF, two unresolved targets detectors are proposed using the generalized likelihood ratio test. The two detectors are for the cases with and without knowledge of one target's direction-of-arrival, respectively. The proposed detectors are evaluated via Monte Carlo simulations and compared with their counterparts that consider only one angular dimension. The results show that performance improvement is achieved through joint processing of the two angular dimensions.