Jellema, Willem

Murphy, J. A.

Trappe, Neil

Wild, Wolfgang

Withington, S.

English

In many submillimeter-wave optical systems performance is in some way affected by the presence of standing waves. Usually these effects are studied empirically or only modeled to first-order by assuming a quasi-sinusoidal variation with distance and wavelength. In this paper we present an analytical technique to calculate the coupling between two corrugated horns including the total transmission and reflection properties. In our model we have combined the waveguide mode matching technique with a Gaussian beam modedescription of the free space propagation. We illustrate the approach for the case of two coupled corrugated horns as the distance between them is varied. We furthermore present experimental test results confirming that multiple reflections do not always result in a classical periodic standing wave pattern. In particular when the horns are close together and the fields are not well matched, high Q cavity effects are observed resulting in irregular standing wave patterns. These cavity effects can be attributed to high-order modes which get trapped between transmitting and receiving horn. We finally discuss the consequences of our observations for a few examples of typical quasi-opticalarrangements illustrating that the presented effects can have important consequences for submillimeter-wave optical systems

Dissertations of the University of Groningen

   University of GroningenModal Analysis and Experimental Study of High-Order Mode Contribution to Standing Wavesin Quasi-Optical SystemsJellema, Willem; Withington, S.; Trappe, Neil; Murphy, J. A.; Wild, WolfgangIMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite fromit. Please check the document version below.Document VersionPublisher's PDF, also known as Version of recordPublication date:2004Link to publication in University of Groningen/UMCG research databaseCitation for published version (APA):Jellema, W., Withington, S., Trappe, N., Murphy, J. A., & Wild, W. (2004). Modal Analysis and ExperimentalStudy of High-Order Mode Contribution to Standing Waves in Quasi-Optical Systems. Abstract from 15thInternational Symposium on Space Teraherb Technolog, Northampton, MA, United States.CopyrightOther than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of theauthor(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).The publication may also be distributed here under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license.More information can be found on the University of Groningen website: https://www.rug.nl/library/open-access/self-archiving-pure/taverne-amendment.Take-down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons thenumber of authors shown on this cover page is limited to 10 maximum.Download date: 12-10-202215th International Symposium on Space Teraherb TechnologyModal Analysis and Experimental Study of High-Order ModeContribution to Standing Waves in Quasi-Optical SystemsWillem Jellema 1 '4, Stafford Withington2, Neil Trappe3, J. Anthony Murphy3,Wolfgang Wild1'4'Space Research Organization of the Netherlands (SRON), P.O. Box 800, 9700 AVGroningen, the Netherlands2Cavendish Laboratory, Madingley Road, Cambridge CB3 OHE, United Kingdom3National University of Ireland Maynooth, Co, Kildare, Maynooth, Ireland4Kapteyn Institute, P.O. Box 800, 9700 AV Groningen, the NetherlandsIn many submillimeter-wave optical systems performance is in some way affected by thepresence of standing waves. Usually these effects are studied empirically or only modeledto first-order by assuming a quasi-sinusoidal variation with distance and wavelength. Inthis paper we present an analytical technique to calculate the coupling between twocorrugated horns including the total transmission and reflection properties. In our modelwe have combined the waveguide mode matching technique with a Gaussian beam modedescription of the free space propagation. We illustrate the approach for the case of twocoupled corrugated horns as the distance between them is varied. We furthermore presentexperimental test results confirming that multiple reflections do not always result in aclassical periodic standing wave pattern. In particular when the horns are close togetherand the fields are not well matched, high Q cavity effects are observed resulting inirregular standing wave patterns. These cavity effects can be attributed to high-ordermodes which get trapped between transmitting and receiving horn. We finally discuss theconsequences of our observations for a few examples of typical quasi-opticalarrangements illustrating that the presented effects can have important consequences forsubmillimeter-wave optical systems.264

Modal Analysis and Experimental Study of High-Order Mode Contribution to Standing Waves in Quasi-Optical Systems

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Modal Analysis and Experimental Study of High-Order Mode Contribution to Standing Waves in Quasi-Optical Systems

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