Angle Estimation of Extended Targets in Main-Lobe Interference With Polarization Filtering

In the presence of the interference from a main-lobe direction, the monopulse measurements always get erroneous angle estimates. By polarization filtering, the interference can be suppressed. However, an error from the cross-polarization of the target and the unpolarized component of the interference is introduced in the monopulse processing. To effectively extract the angle of the extended target accurately after polarization filtering, duplex polarization filtering and polarization filtering extractor based on a covariance matrix are developed. In addition, it can be found that the variance of the angle estimates varies when the polarizations of the target and the interference fluctuate, which degrades the performance of the tracking filter. For this problem, an adaptive fixed-gain filter for stabilizing the variance of the target angle estimates is proposed.