Translator Disclaimer
Paper
27 June 2006 Elevation angle dependence of the SMA antenna focus position
Author Affiliations +
Abstract
We report the measurement results and compensation of the antenna elevation angle dependences of the Submillimeter Array (SMA) antenna characteristics. Without optimizing the subreflector (focus) positions as a function of the antenna elevation angle, antenna beam patterns show lopsided sidelobes, and antenna efficiencies show degradations. The sidelobe level increases and the antenna efficiencies decrease about 1% and a few %, respectively, for every 10° change in the elevation angle at the measured frequency of 237 GHz. We therefore obtained the optimized subreflector positions for X (azimuth), Y (elevation), and Z (radio optics) focus axes at various elevation angles for all the eight SMA antennas. The X axis position does not depend on the elevation angle. The Y and Z axes positions depend on the elevation angles, and are well fitted with a simple function for each axis with including a gravity term (cosine and sine of elevation, respectively). In the optimized subreflector positions, the antenna beam patterns show low level symmetric sidelobe of at most a few%, and the antenna efficiencies stay constant at any antenna elevation angles. Using one set of fitted functions for all antennas, the SMA is now operating with real-time focusing, and showing constant antenna characteristics at any given elevation angle.
© (2006) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Satoki Matsushita, Masao Saito, Kazushi Sakamoto, Todd R. Hunter, Nimesh A. Patel, Tirupati K. Sridharan, and Robert W. Wilson "Elevation angle dependence of the SMA antenna focus position", Proc. SPIE 6275, Millimeter and Submillimeter Detectors and Instrumentation for Astronomy III, 62751W (27 June 2006); https://doi.org/10.1117/12.670642
PROCEEDINGS
10 PAGES


SHARE
Advertisement
Advertisement
RELATED CONTENT

Commissioning status of the Greenland Telescope (GLT)
Proceedings of SPIE (July 06 2018)
Overview of engineering activities at the SMA
Proceedings of SPIE (July 12 2008)
CHAMP<sup>+</sup>: a powerful array receiver for APEX
Proceedings of SPIE (June 27 2006)
Characterization of a 200-GHz SIS mixer
Proceedings of SPIE (July 31 1998)

Back to Top