McCarthy, Darragh and Trappe, Neil and Murphy, J.Anthony and Gradziel, Marcin and O'Sullivan, Créidhe and Doherty, Stephen (2015) The Optimisation and Analysis of Multi-moded Feed Horn Structures at Terahertz Frequencies. In: PIERS 2015 in Prague Proceedings, July 6-9, 2015, Prague, Czech Republic. The Electromagnetics Academy, pp. 2268-2272. ISBN 9781934142301

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Abstract

Carrying out astronomical observations at far-infrared wavelengths is critical in enabling further progress in the fields of cosmology and astrophysics. Such observations will allow additional insight into the birth and evolution of the Universe. To allow progress in these areas, it is necessary to improve the sensitivity and resolution of the instrumentation that is used to carry out these observations. At the high frequencies in question (terahertz), the instruments typically make use of horn antenna fed detector systems. To achieve the required performance, the horn designs must be highly optimised. Full electromagnetic solvers (CST, HFSS, COMSOL etc.) struggle to predict the performance of horn antennas at such high frequencies in a timely manner due to the large electrical size of the structures. It is therefore very challenging to perform the optimisation using such solvers particularly for multi-mode systems where each mode would have to be considered individually. In this paper we outline an alternative technique for modelling multi-mode (partially coherent) horn antennas based on the mode-matching technique, which allows electrically large structures to be modelled in a highly efficient manner. This technique returns a set of scattering matrices which gives a full vector definition of the transmission and re ection characteristics of the resulting design at a given frequency. We demonstrate how this can be used to extract field patterns and other figures of merit that are important for evaluating the electromagnetic performance of a horn design. An efficient genetic algorithm based optimisation technique (using mode-matching) is also presented. The optimisation process is based on a piecewise conical profile horn design and produces a geometry that is optimised with respect to some figure of merit that is of critical importance for the application in question. This allows the instrument to realise the high levels of optical performance that are required for astronomical applications.

Item Type:	Book Section
Additional Information:	The authors wish to acknowledge the ¯nancial support of the European Space Agency under the Irish Announcement of Opportunity scheme and the Irish Research Council EMBARK initiative.
Keywords:	far-infrared; Multi-moded Feed Horn Structures; Terahertz Frequencies;
Academic Unit:	Faculty of Science and Engineering > Experimental Physics
Item ID:	13783
Depositing User:	Dr. Marcin Lukasz Gradziel
Date Deposited:	07 Jan 2021 15:42
Journal or Publication Title:	PIERS Proceedings
Publisher:	The Electromagnetics Academy
Refereed:	Yes
Funders:	European Space Agency, Irish Research Council (IRC)
URI:	Publisher
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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