Identifying narrow-band mutual coupling resonances in SKA-low stations using frequency-independent current basis functions
Abstract
Mutual coupling between closely spaced elements in aperture arrays introduces narrow-band spectral features in the Embedded Element Patterns (EEPs), threatening measurements of the 21-cm power spectrum with instruments such as SKA-low. We detail a method to identify such features through the construction of frequency-independent current basis functions, utilising a singular value decomposition of frequency-dependent basis functions. We demonstrate the method on a three-element linear array and full pseudo-random station of SKA log-periodic antennas and examine the current power induced by mutual coupling. For the pseudo-random layout station we note many narrow-band resonance features, including strong resonances at 50.8~MHz and 83.6~MHz, where the coupled power on the passive antennas can approach or exceed that of the excited antenna. Simulated delay power spectra for the SKA-low core show that observing in frequency bands including resonance features causes large foreground leakage within the delay power spectra, obscuring the EoR window. For the pseudo-random layout station with SKALA4.0 we identify two significant frequency bands from 59.2--76.2~MHz and 84.2--103.3~MHz which are free of contamination from current resonances, preserving the EoR window in these frequency ranges.
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BibTeX
@misc{cumner2026identifying,
title = {{Identifying narrow-band mutual coupling resonances in SKA-low stations using frequency-independent current basis functions}},
author = {John Cumner and Oscar S. D. O'Hara and Quentin Gueuning and Anthony Brown and Fred Dulwich and Oskar Zetterstrom},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.40008},
eprint = {2610.40008},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.40008},
}
RIS
TY - UNPB
TI - Identifying narrow-band mutual coupling resonances in SKA-low stations using frequency-independent current basis functions
AU - John Cumner
AU - Oscar S. D. O'Hara
AU - Quentin Gueuning
AU - Anthony Brown
AU - Fred Dulwich
AU - Oskar Zetterstrom
PY - 2026
DA - 2026/10/29
PB - arXiv
DO - 10.48550/arxiv.2610.40008
UR - https://arxiv.org/abs/2610.40008
AB - Mutual coupling between closely spaced elements in aperture arrays introduces narrow-band spectral features in the Embedded Element Patterns (EEPs), threatening measurements of the 21-cm power spectrum with instruments such as SKA-low. We detail a method to identify such features through the construction of frequency-independent current basis functions, utilising a singular value decomposition of frequency-dependent basis functions. We demonstrate the method on a three-element linear array and full pseudo-random station of SKA log-periodic antennas and examine the current power induced by mutual coupling. For the pseudo-random layout station we note many narrow-band resonance features, including strong resonances at 50.8~MHz and 83.6~MHz, where the coupled power on the passive antennas can approach or exceed that of the excited antenna. Simulated delay power spectra for the SKA-low core show that observing in frequency bands including resonance features causes large foreground leakage within the delay power spectra, obscuring the EoR window. For the pseudo-random layout station with SKALA4.0 we identify two significant frequency bands from 59.2--76.2~MHz and 84.2--103.3~MHz which are free of contamination from current resonances, preserving the EoR window in these frequency ranges.
ER -