Clutter mitigation using auxiliary elements for the NWRT phased array radar

The national weather radar testbed (NWRT) has a 10-cm phased array radar that is used primarily for monitoring the weather. It is attractive compared to the current parabolic dish weather surveillance radar-88 Doppler (WSR-88D) because of its capability to electronically steer. When combined with the recently developed beam multiplexing technique that uses a small number of contiguous samples and clever spatial sampling, this radar can obtain very rapid update scans and is extremely advantageous in monitoring severe weather. However, the small number of contiguous samples makes filtering of the clutter signal problematic in the temporal/spectral domain and can limit the performance of this radar in clutter dominated conditions. By exploiting the spatial correlation of the auxiliary channel signals, the effect of clutter contamination can be reduced to overcome this problem. In this work, two spatial filtering techniques that use low-gain auxiliary receive channels are presented, and the effect of clutter mitigation is investigated using numerical simulations for a tornadic thunderstorm dominated by clutter return. Parameters under investigation include signal-to-noise ratio, clutter-to-signal ratio, number of time series samples, varying clutter spectral widths, and maximum weight constraints.