Performance of Polarimetric Beamformers for Phased Array Radio Telescopes

TL;DR

This paper compares four advanced beamforming schemes for phased array radio telescopes, evaluating their sensitivity and polarization accuracy using a practical prototype, and highlights differences in their polarization state solutions.

Contribution

It introduces and compares four recent beamforming schemes, analyzing their performance in sensitivity and polarization accuracy for phased array radio telescopes.

Findings

All four beamformers have similar sensitivity.

Different beamformers produce varying polarization states.

Some beamformers yield sub-optimal polarization solutions.

Abstract

The results of four recently introduced beamforming schemes for phased array systems are discussed, each of which is capable to provide high sensitivity and accurate polarimetric performance of array-based radio telescopes. Ideally, a radio polarimeter should recover the actual polarization state of the celestial source, and thus compensate for unwanted polarization degradation effects which are intrinsic to the instrument. In this paper, we compare the proposed beamforming schemes through an example of a practical phased array system (APERTIF prototype) and demonstrate that the optimal beamformer, the max-SLNR beamformer, the eigenvector beamformer, and the bi-scalar beamformer are sensitivity equivalent but lead to different polarization state solutions, some of which are sub-optimal.