Characterization of a Low-Frequency Radio Astronomy Prototype Array in Western Australia

TL;DR

This paper presents the characterization of a prototype low-frequency radio array, AAVS0.5, using both astronomical interferometry and detailed simulations, to inform the design of next-generation radio telescopes like the SKA.

Contribution

It introduces a novel dual-method approach combining in-situ interferometry and full-wave simulation for array characterization, enhancing design accuracy for future radio telescopes.

Findings

Array sensitivity measurements match simulations within expected uncertainties.

Beam pattern characterization reveals areas for design improvement.

Dual-method approach proves effective for array validation.

Abstract

We report characterization results for an engineering prototype of a next-generation low-frequency radio astronomy array. This prototype, which we refer to as the Aperture Array Verification System 0.5 (AAVS0.5), is a sparse pseudo-random array of 16 log-periodic antennas designed for 70-450 MHz. It is co-located with the Murchison Widefield Array (MWA) at the Murchison Radioastronomy Observatory (MRO) near the Australian Square Kilometre Array (SKA) core site. We characterize the AAVS0.5 using two methods: in-situ radio interferometry with astronomical sources and an engineering approach based on detailed full-wave simulation. In-situ measurement of the small prototype array is challenging due to the dominance of the Galactic noise and the relatively weaker calibration sources easily accessible in the southern sky. The MWA, with its 128 "tiles" and up to 3 km baselines, enabled in-situ measurement via radio interferometry. We present array sensitivity and beam pattern characterization results and compare to detailed full-wave simulation. We discuss areas where differences between the two methods exist and offer possibilities for improvement. Our work demonstrates the value of the dual astronomy-simulation approach in upcoming SKA design work.