We present a smooth-walled feedhorn with cross polarization and reflected power lower than -30 dB across the entire 30% bandwidth. A prototype feedhorn has been fabricated, and the wide-band, low-cross polarization performance has been demonstrated. The feedhorn has a circular aperture and monotonically narrows towards an input waveguide interface. This allows it to be manufactured by progressively milling the profile using a set of custom tools. This is especially useful in applications where a large number of feeds are desired in a planar array format. Such applications include astronomical cameras in millimeter waveband that require large arrays of detectors for future increases in mapping speed and sensitivity. Specifically, large arrays of feedhorns are well-matched to the problem of measuring the polarization of the cosmic microwave background to search for the faint signature of inflation, as they provide good beam control, the requisite sensitivity, and compatibility with low-noise bolometric detectors.

Date Published: 15 July 2010
PDF: 9 pages
Proc. SPIE 7741, Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy V, 774129 (15 July 2010); doi: 10.1117/12.857679

Published in SPIE Proceedings Vol. 7741:
Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy V
Wayne S. Holland; Jonas Zmuidzinas, Editor(s)