Holographic Calibration of Phased Array Telescopes

TL;DR

This paper introduces a rapid, resource-efficient holographic calibration method for phased array telescopes that does not require a reference antenna, demonstrated on SKA prototype data.

Contribution

It presents a novel holographic calibration technique for phased array telescopes that is quick, resource-efficient, and applicable without a reference antenna.

Findings

Effective calibration demonstrated on SKA prototype data

Method suitable for initial commissioning and routine calibration

Works without a reference antenna

Abstract

In radio astronomy, holography is a commonly used technique to create an image of the electric field distribution in the aperture of a dish antenna. The image is used to detect imperfections in the reflector surface. Similarly, holography can be applied to phased array telescopes, in order to measure the complex gains of the receive paths of individual antennas. In this paper, a holographic technique is suggested to calibrate the digital beamformer of a phased array telescope. The effectiveness of the technique was demonstrated by applying it on data from the Engineering Development Array 2, one of the prototype stations of the low frequency component of the Square Kilometre Array. The calibration method is very quick and requires few resources. In contrast to holography for dish antennas, it works without a reference antenna. We demonstrate the utility of this technique for initial station commissioning and verification as well as for routine station calibration.