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    Corrugated waveguide band edge filters for CMB experiments in the far infrared


    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

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    Abstract

    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.

    Item Type: Article
    Additional Information: The definitive version of this article is available at DOI: 10.1016/j.infrared.2004.10.001 . The authors wish to acknowledge the financial assistance of Enterprise Ireland, the Irish Research Council for Science and Technology: IRCSET (Embark award) and the National University of Ireland Maynooth (Daniel O’Connell Fellowship).
    Keywords: Band edge; Filters; CMB; Corrugated horns;
    Academic Unit: Faculty of Science and Engineering > Experimental Physics
    Item ID: 5935
    Identification Number: https://doi.org/10.1016/j.infrared.2004.10.001
    Depositing User: Dr. Créidhe O'Sullivan
    Date Deposited: 04 Mar 2015 17:02
    Journal or Publication Title: Infrared Physics & Technology
    Publisher: Elsevier
    Refereed: Yes
    Funders: Irish Research Council for Science Engineering and Technology (IRCSET)
    URI:

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