The self-cohering tied-array

TL;DR

This paper analyzes how atmospheric turbulence affects the performance of radio interferometers in tied-array mode and proposes a calibration method to mitigate phase errors, supported by simulations.

Contribution

It provides statistical estimates of atmospheric impact on tied-array effectiveness and introduces a new calibration technique using optimization methods.

Findings

Atmospheric turbulence significantly reduces effective area at various frequencies.

The proposed calibration method improves tied-array performance in simulations.

Phase errors can be effectively mitigated with the new calibration approach.

Abstract

Large radio astronomy multi-element interferometers are frequently used as single dishes in a tied-array mode when signals from separate antennas are added. Phase shifts arising during wave propagation through a turbulent atmosphere can significantly reduce the effective area of an equivalent single dish. I aim to give estimates of the impact of the ionosphere and troposphere on the effectiveness of a radio interferometer working in tied-array mode. Statistical estimates of the effective area are calculated and the power-law of turbulent atmosphere irregularities has been used. A simple method of tied-array calibration using optimization techniques is proposed. The impact of phase errors on the effectiveness of tied-arrays are given for low and high frequencies. Computer simulations demonstrate the efficacy of the proposed calibration algorithm.