Spectral performance of SKA Log-periodic Antennas I: Mitigating spectral artefacts in SKA1-LOW 21-cm cosmology experiments

Eloy de Lera Acedo; Cathryn M. Trott; Randall B. Wayth; Nicolas Fagnoni; Gianni Bernardi; Brett Wakley; Leon V. E. Koopmans; Andrew J. Faulkner; Jan Geralt bij de Vaate

doi:10.1093/mnras/stx904

arXiv · 1702.05126

Spectral performance of SKA Log-periodic Antennas I: Mitigating spectral artefacts in SKA1-LOW 21-cm cosmology experiments

Eloy de Lera Acedo·Cathryn M. Trott·Randall B. Wayth·Nicolas Fagnoni·Gianni Bernardi·Brett Wakley·Leon V. E. Koopmans·Andrew J. Faulkner·Jan Geralt bij de Vaate

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Abstract

This paper is the first in a series of papers describing the impact of antenna instrumental artefacts on the 21-cm cosmology experiments to be carried out by the low frequency instrument (SKA1-LOW) of the Square Kilometre Array telescope (SKA), i.e., the Cosmic Dawn (CD) and the Epoch of Reionization (EoR). The smoothness of the passband response of the current log-periodic antenna being developed for the SKA1-LOW is analyzed using numerical electromagnetic simulations. The amplitude variations over the frequency range are characterized using low-order polynomials defined locally, in order to study the impact of the passband smoothness in the instrument calibration and CD/EoR Science. A solution is offered to correct a fast ripple found at 60~MHz during a test campaign at the SKA site at the Murchison Radio-astronomy Observatory, Western Australia in September 2015 with a minor impact on the telescope's performance and design. A comparison with the Hydrogen Epoch of Reionization Array antenna is also shown demonstrating the potential use of the SKA1-LOW antenna for the Delay Spectrum technique to detect the EoR.

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Eloy de Lera Acedo, Cathryn M. Trott, Randall B. Wayth, Nicolas Fagnoni, Gianni Bernardi, Brett Wakley, Leon V. E. Koopmans, Andrew J. Faulkner, Jan Geralt bij de Vaate. 2017-04-10. Spectral performance of SKA Log-periodic Antennas I: Mitigating spectral artefacts in SKA1-LOW 21-cm cosmology experiments. https://doi.org/10.1093/mnras%2Fstx904

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