# Primary beam effects of radio astronomy antennas -- II. Modelling the MeerKAT L-band beam

## TL;DR

This paper develops a detailed, sparse model of MeerKAT's L-band primary beam using observations and simulations, enhancing calibration and imaging accuracy for radio astronomy.

## Contribution

It introduces a novel Zernike polynomial-based beam model and software tool for improved direction-dependent calibration of MeerKAT antennas.

## Key findings

- Model is more accurate for diagonal beam elements and at lower frequencies.
- Provides a software tool (EIDOS) for beam modeling and calibration.
- Future improvements expected with more precise measurements and simulations.

## Abstract

After a decade of design and construction, South Africa's SKA-MID precursor MeerKAT has begun its science operations. To make full use of the widefield capability of the array, it is imperative that we have an accurate model of the primary beam of its antennas. We have taken available L-band full-polarization 'astro-holographic' observations of three antennas and a generic electromagnetic simulation and created sparse representations of the beams using principal components and Zernike polynomials. The spectral behaviour of the spatial coefficients has been modelled using discrete cosine transform. We have provided the Zernike-based model over a diameter of 10 deg averaged over the beams of three antennas in an associated software tool (EIDOS) that can be useful in direction-dependent calibration and imaging. The model is more accurate for the diagonal elements of the beam Jones matrix and at lower frequencies. As we get more accurate beam measurements and simulations in the future, especially for the cross-polarization patterns, our pipeline can be used to create more accurate sparse representations of MeerKAT beams.