ISSTT Proceedings

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A Novel Full Waveguide Band Orthomode

Authors:
Gopal Narayanan, Neal R. Erickson
Abstract:
At millimeter and submillimeter wavelengths, cryogenically cooled receivers based on STS and HEB technologies are approaching the quantum limit in noise temperature. Further increase in sensitivity can be obtained by using dual-polarized operation. One of the principal components of a dual-polarization receiver is a polarization diplexer or orthomode transducer (0MT). Traditionally the OMT used in radio astronomy receivers is the wire grid, which can be large and bulky. A waveguide based OMT, on the other hand, can be integrated with the mixer blocks and cryogenically cooled thereby reducing ohmic losses. A waveguide based OMT also lends itself well to integration into focal-plane array receivers. In this paper, we present the design of a novel OMT that can be constructed using conventional split-block techniques. The design is based on the proposed Bøifot OMT by Wollack, but has been considerably modified to (a) make it easy to fabricate, and (b) make it scalable to ~ 1 THz. The return loss is —20 dB or better over a full waveguide-band (~ 40% bandwidth), and the cross-polarization and isolation are better than —70 dB. Design details of a W-band OMT are presented.
Categories:
Circuits, Optics
Year:
2002
Session:
10
Full-text:
Download a PDF of this paper.
Page Number(s):
505-514