19 April 2023 Holographic phase-retrieval method of near-field antenna pattern measurement for bolometer-array-equipped millimeter-wave telescopes
Author Affiliations +
Abstract

Wide field-of-view millimeter-wave telescopes with a bolometric detector array have been developed for cosmic microwave background radiation observations. For the purpose of laboratory verification of these telescopes, several studies have demonstrated near-field antenna measurements using a phase-sensitive detector that replaces a few representative pixels of the focal-plane detector array. We present a holographic phase-retrieval method that enables near-field measurements with the bolometric detector array as it is. We place a reference emitter at a fixed position and scan a signal emitter at the telescope aperture. These two emitters are phase-locked and generate interference patterns (holograms) on the focal plane, from which the amplitude and phase of the aperture field can be retrieved. We experimentally demonstrated this method with a crossed-Dragone telescope with a field-of-view that is 18 deg × 9 deg. In the demonstration, we placed a phase-sensitive detector at three detector positions on the focal plane. The antenna patterns calculated from the hologram, neglecting the directly measured phase information, were consistent with those calculated from both intensity and phase measurements at the −60-dB level at 180 GHz. Applying this method, the antenna patterns for all of the bolometric detectors on the focal plane can theoretically be measured simultaneously.

© 2023 Society of Photo-Optical Instrumentation Engineers (SPIE)
Ryo Nakano, Hayato Takakura, Yutaro Sekimoto, Junji Inatani, Masahiro Sugimoto, Shugo Oguri, and Frederick Matsuda "Holographic phase-retrieval method of near-field antenna pattern measurement for bolometer-array-equipped millimeter-wave telescopes," Journal of Astronomical Telescopes, Instruments, and Systems 9(2), 028003 (19 April 2023). https://doi.org/10.1117/1.JATIS.9.2.028003
Received: 17 November 2022; Accepted: 3 April 2023; Published: 19 April 2023
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KEYWORDS
Antennas

Near field

Holography

Telescopes

Holograms

Phase measurement

Polarization

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