Murphy, J.Anthony and Trappe, Neil and Withington, Stafford (2003) Gaussian beam mode analysis of partial reflections in simple quasi-optical systems fed by horn antennas. Infrared Physics & Technology, 44 (4). pp. 289-297. ISSN 1350-4495

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Abstract

Low-level reflections are particularly troublesome in sensitive high-resolution spectral line receivers in the submillimetre and terahertz wavebands, giving rise to baseline ripple on spectra which is hard to distinguish from wide lines. In typical systems for submillimetre-wave astronomy, for example, a lens or flat dielectric plate is often used as a cryostat window placed close to a feed horn. Partial reflection from such interfaces can give rise to return loss at the horn throat, which is considerably higher than for the horn radiating into free space. A full scattering matrix approach based on a combination of standard waveguide modes and quasi-optical Gaussian beam modes can be used to analyse standing waves due to partial reflections, in which track is kept of both the backward and forward going components of the propagating fields. In this paper, we consider how such an analytical tool can be set up and we present typical examples of interest in which horn antennas feed simple components including windows, lenses and reflecting central blockages.

Item Type:	Article
Additional Information:	The authors wish to acknowledge the financial assistance of Enterprise Ireland, for partially funding this research. Neil Trappe is appreciative of the support of NUIM through a Daniel O'Connell Scholarship.
Keywords:	Submillimetre-wave receivers; Quasi-optics; Standing waves;
Academic Unit:	Faculty of Science and Engineering > Experimental Physics
Item ID:	9835
Identification Number:	https://doi.org/10.1016/S1350-4495(03)00127-0
Depositing User:	Dr. Neil Trappe
Date Deposited:	27 Aug 2018 14:47
Journal or Publication Title:	Infrared Physics & Technology
Publisher:	Elsevier
Refereed:	Yes
Funders:	Enterprise Ireland (EI)
URI:	https://www.sciencedirect.com
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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