Feedback-Controlled Beam Pattern Measurement Method Using a Power-Variable Calibration Source for Cosmic Microwave Background Telescopes
Abstract
We demonstrate a novel beam pattern measurement method for the side lobe characterization of cosmic microwave background telescopes. The method employs a power-variable artificial microwave source under feedback control from the detector under test on the telescope. It enables us to extend the dynamic range of the beam pattern measurement without introducing nonlinearity effects from the detector. We conducted a laboratory-based proof-of-concept experiment, measuring the H-plane beam pattern of a horn antenna coupled to a diode detector at 81 GHz. We gained an additional dynamic range of 60.3 dB attributed to the feedback control. In addition, we verified the measurement by comparing it with other reference measurements obtained using conventional methods. The method is also applicable to general optical measurements requiring a high dynamic range to detect subtle nonidealities in the characteristics of optical devices.
Cite
@article{arxiv.2509.09386,
title = {Feedback-Controlled Beam Pattern Measurement Method Using a Power-Variable Calibration Source for Cosmic Microwave Background Telescopes},
author = {Haruaki Hirose and Masaya Hasegawa and Daisuke Kaneko and Taketo Nagasaki and Ryota Takaku and Tijmen de Haan and Satoru Takakura and Takuro Fujino},
journal= {arXiv preprint arXiv:2509.09386},
year = {2026}
}
Comments
20 pages, 9 figures, revised after referee review