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, Léon 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 analysed 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 2015 September 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.
Original languageEnglish
Pages (from-to)2662-2671
Number of pages10
JournalMonthly Notices of the Royal Astronomical Society
Volume469
Issue number3
DOIs
Publication statusPublished - 1-Aug-2017

Keywords

  • instrumentation: detectors
  • dark ages
  • reionization
  • first stars
  • LIMITATIONS
  • WINDOWS
  • POWER SPECTRUM
  • REIONIZATION ARRAY
  • HYDROGEN EPOCH
  • POLARIZATION LEAKAGE
  • SCIENCE IMPLICATIONS
  • FOREGROUNDS
  • SIMULATIONS
  • CALIBRATION

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