Beamspace techniques for hot clutter cancellation

In airborne radar applications, hot clutter refers to terrain-reflected jammer multipath interference which is spatially distributed throughout the mainbeam and sidelobes of the radar receiver. Most current cancellation methods use a single reference beam to cancel the mainbeam hot clutter interference. However these cancellers are computationally intensive and suffer from blind interval effects due to the size of the temporal window required for effective mitigation. We propose a full beamspace canceller implemented as a generalized sidelobe canceller for hot clutter mitigation. The proposed canceller exploits the spatial nature of the interference by utilizing delayed replicas of the jammer signal at all azimuth angles to significantly reduce the temporal extent of the canceller. By trading off temporal for spatial degrees of freedom, the full beamspace approach is able to drastically reduce the size of the temporal window required, achieving effective cancellation with fewer total degrees of freedom and a significant reduction in the blind interval. Results comparing the proposed full beamspace and the single-beam cancellers are reported using data collected in the Mountaintop program