Multichannel nullforming at the National Weather Radar Testbed

Standard clutter filtering techniques in meteorological applications are limited to temporal filtering of radar data gathered by a single receiver. Using spatial data collected by the multi-channel receiver at the National Weather Radar Testbed phased array radar, novel clutter filtering techniques can be applied to meterological data. The spatial data collected by the sidelobe canceller channels is manipulated using linearly constrained minimum power (LCMP) beamforming with a quadratic constraint; constraints are selected to reject data from the sidelobes that is common to the sidelobe canceller channels and the sum channel, introducing nulls in the direction of ground clutter into the received beampattern and filtering out the clutter. This method of beamforming has proven effective in other fields, but has not yet been applied to meteorological surveillance radars. This paper explores the efficacy and efficiency of several methods of nullforming using data collected at the National Weather Radar Testbed.