Kalinauskaite, E;
Murphy, JA;
McAuley, I;
Trappe, NA;
McCarthy, DN;
Bracken, CP;
Doherty, S;
... Savini, G; + view all
(2017)
Radiation Patterns of Multimode Feed-Horn Coupled Bolometers for FAR-IR Space Applications.
In: Sadwick, LP and Yang, T, (eds.)
(Proceedings) Conference on Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications X.
SPIE - The International Society for Optics and Photonics
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Abstract
A multimode horn differs from a single mode horn in that it has a larger sized waveguide feeding it. Multimode horns can therefore be utilized as high efficiency feeds for bolometric detectors, providing increased throughput and sensitivity over single mode feeds, while also ensuring good control of the beam pattern characteristics. Although a cavity mounted bolometer can be modelled as a perfect black body radiator (using reciprocity in order to calculate beam patterns), nevertheless, this is an approximation. In this paper we present how this approach can be improved to actually include the cavity coupled bolometer, now modelled as a thin absorbing film. Generally, this is a big challenge for finite element software, in that the structures are typically electrically large. However, the radiation pattern of multimode horns can be more efficiently simulated using mode matching, typically with smooth-walled waveguide modes as the basis and computing an overall scattering matrix for the horn-waveguide-cavity system. Another issue on the optical efficiency of the detectors is the presence of any free space gaps, through which power can escape. This is best dealt with treating the system as an absorber. Appropriate reflection and transmission matrices can be determined for the cavity using the natural eigenfields of the bolometer cavity system. We discuss how the approach can be applied to proposed terahertz systems, and also present results on how the approach was applied to improve beam pattern predictions on the sky for the multi-mode HFI 857GHz channel on Planck. © (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
| Type: | Proceedings paper |
|---|---|
| Title: | Radiation Patterns of Multimode Feed-Horn Coupled Bolometers for FAR-IR Space Applications |
| Event: | Conference on Terahertz, RF, Millimeter, and Submillimeter-Wave Technology and Applications X |
| Location: | San Francisco, CA |
| Dates: | 30 January 2017 - 02 February 2017 |
| ISBN-13: | 978-1-5106-0648-7 |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1117/12.2249869 |
| Publisher version: | http://doi.org/10.1117/12.2249869 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Science & Technology, Technology, Physical Sciences, Engineering, Electrical & Electronic, Optics, Physics, Applied, Engineering, Physics |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1561916 |
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