Cross-Polar Canceller (XPC): A Technique to Reduce Cross-Polar Pattern Contamination in Polarimetric Weather Observations

This paper proposes a novel technique to improve cross-polar isolation for polarimetric phased array antennas used for meteorological observations, referred to as cross-polar canceller (XPC). It is based on the use of canceller antenna elements transmitting a scaled version of the original waveform in the polarization where the cross-polar contamination is observed but with opposite phase. The technique involves calculating the correct number of canceller elements, their location in the array, and a scaling factor for the amplitude and phase of the selected canceller elements such that maximum cross-polar isolation is possible. It is intended for dual-polarization, fully digital, phased array radar systems. It can also be applied to sub-array architectures if amplitude and phase control is possible at the element level. Previous similar efforts illustrated the potential of this technique for the alternating transmission/reception of horizontally and vertically polarized waves. In this paper, we present progress towards using this technique for the simultaneous transmission/reception of horizontally and vertically polarized waves. Preliminary results show that this technique is capable to improve cross-polar isolation by 15 dB on average, at the cost of similar to 0.32 dB loss in copolar pattern gain per canceller element used. The XPC technique is being implemented in the Horus system, an S-band, polarimetric, fully digital phased array system developed by the Advanced Radar Research Center (ARRC) at the University of Oklahoma (OU).