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Corrugated waveguide band edge filters for CMB experiments in the far infrared
Gleeson, E.; Murphy, J.Anthony; Maffei, B.; Lanigan, W.; Brossard, J.; Cahill, G.; Cartwright, E.; Church, S.E.; Hinderks, J.; Kirby, E.; O'Sullivan, Créidhe
Millimetre wave corrugated waveguide-horn structures are used as both single-moded and multi-moded bolometer feeds in a number of cosmic microwave background (CMB) experiments (e.g. PLANCK, Archeops, QUaD). Such horns tend to be employed over a relatively wide bandwidth and for single-moded horns the waveguide acts as the high pass filter. In this paper we report on our investigation on how the waveguide details determine the exact location of the low frequencyband edge of such corrugated horns. A sharp step-like band edge, below which there is negligible propagation, is ideallyrequired. Furthermore anyleakage below the expected cut-off, possible in corrugated guides, could lead to non-idealised cross-polar effects. Typically deeper corrugations are required in the waveguide filter than at the horn aperture for wide bandwidth operation, thus necessitating a transition section over which the corrugation depth smoothlyvaries. An electromagnetic mode matching technique and a surface impedance hybrid mode model are used to compute the horn transmission characteristics. We have also undertaken laboratorymeasurements of the band edge of prototype corrugated horns in order to test the models.
Keyword(s): Experimental Physics; Band edge; Filters; CMB; Corrugated horns
Publication Date:
2005
Type: Journal article
Peer-Reviewed: Yes
Institution: Maynooth University
Citation(s): Gleeson, E. and Murphy, J.Anthony and Maffei, B. and Lanigan, W. and Brossard, J. and Cahill, G. and Cartwright, E. and Church, S.E. and Hinderks, J. and Kirby, E. and O'Sullivan, Créidhe (2005) Corrugated waveguide band edge filters for CMB experiments in the far infrared. Infrared Physics & Technology, 46. pp. 493-505. ISSN 1350-4495
Publisher(s): Elsevier
File Format(s): other
Related Link(s): http://eprints.maynoothuniversity.ie/5935/1/COS-Corrugated-Waveguide.pdf
First Indexed: 2015-03-06 05:19:26 Last Updated: 2018-09-15 06:13:16