Milimeter-wave Profiled Corrugated Horns for the QUaD Cosmic Background Polarization Experiment

• Main Authors: Murphy, J.Anthony, Gleeson, E., Cahill, G., Lanigan, W., O'Sullivan, Créidhe, Cartwright, E., Church, S.E., Hinderks, J., Kirby, E., Thompson, K., Rusholme, B., Gear, W.K., Maffei, B., Ade, P.A.R., Tucker, C., Jones, B.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Verlag 2005
• Subjects: Experimental Physics; South Pole; South pole
• Online Access: https://mural.maynoothuniversity.ie/5936/; https://mural.maynoothuniversity.ie/5936/1/COS-Millimeter-Wave.pdf

In this paper we report on the design and validation process for the profiled corrugated horn antennas, which feed the bolometer array of a cosmology experiment known as QUaD located at the South Pole. This is a cosmic radiation polarization project, which demands precise knowledge and control of the optical coupling to the signal in order to map the feeble E- and B0polarization mode structure. The system will operate in two millimeter wavelength bands at 100 and 150 GHz. The imaging horn array collects the incoming signal via on-axis front-end optics and a Cassegrain telescope, with a cold stop in front of the array to terminate side-lobe structure at an edge taper of -20dB. The corrugated horn design process was undertaken using in-house analytical software tools, based on modal scattering, specially developed for millimeter-wave profiled horn antennas. An important part of the instrument development was the validation of the horn design, in particular to verify low edge taper levels and the required well-defined band edges. Suitable feed horn designs were measured and were found to be in excellent agreement with theoretical predictions.