A method for improved cross-pol isolation based on the use of auxilliary elements

Abstract

This paper describes a method to answer the following questions: can several of the elements of a phased array be employed as auxiliary (AUX) elements and how can the phase of each be adjusted so that the (1) cross-polarization (cross-pol) isolation is minimized to 40 dB, (2) the sidelobe levels of the main lobe are minimally impacted, and (3) the width and height of the main lobe are minimally impacted? This calibration work is being completed as one component of Lincoln Laboratory's effort within the multifunction phased array radar (MPAR) initiative. Devoting a few of the elements to serve as the AUX channels to specifically operate to mitigate the effects of the cross-pol influence, the distributed sidelobe levels will not suffer much impact; yet, the impact of the AUX elements will have deepened the cross-pol isolation at the peak of the co-polar beam can occur because the AUX elements can achieve a high degree of narrowband angular resolution.

Horus—A Fully Digital Polarimetric Phased Array Radar for Next-Generation Weather Observations

“…This solution to the calibration challenge is an important advantage of fully digital PARs. Further discussion on the use of this approach for the Horus system appears in Section V. Recent work has also shown that polarimetric performance enhancements can be achieved with a fully digital array using the so-called cross-polar canceller (XPC) technique [61], [62], [63]. This method assigns a small number of elements from the entire array in an attempt to mitigate cross-polar contamination by transmitting the opposite phase from the original signal.…”