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Confocal Ellipsoidal Reflector System for a Mechanically Scanned Active Terahertz Imager

Llombart, Nuria and Cooper, Ken B. and Dengler, Robert J. and Bryllert, Tomas and Siegel, Peter H. (2010) Confocal Ellipsoidal Reflector System for a Mechanically Scanned Active Terahertz Imager. IEEE Transactions on Antennas and Propagation, 58 (6). pp. 1834-1841. ISSN 0018-926X.

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We present the design of a reflector system that can rapidly scan and refocus a terahertz beam for high-resolution standoff imaging applications. The proposed optical system utilizes a confocal Gregorian geometry with a small mechanical rotating mirror and an axial displacement of the feed. For operation at submillimeter wavelengths and standoff ranges of many meters, the imaging targets are electrically very close to the antenna aperture. Therefore the main reflector surface must be an ellipse, instead of a parabola, in order to achieve the best imaging performance. Here we demonstrate how a simple design equivalence can be used to generalize the design of a Gregorian reflector system based on a paraboloidal main reflector to one with an ellipsoidal main reflector. The system parameters are determined by minimizing the optical path length error, and the results are validated with numerical simulations from the commercial antenna software package GRASP. The system is able to scan the beam over 0.5 m in cross-range at a 25 m standoff range with less than 1% increase of the half-power beam-width.

Item Type:Article
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Siegel, Peter H.0000-0002-2539-4646
Additional Information:© 2010 IEEE. Manuscript received July 01, 2009; revised November 16, 2009; accepted December 25, 2009. Date of publication March 29, 2010; date of current version June 03, 2010. This work was carried out by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. This work was supported under a contract to the California Institute of Technology, Division of Biology, by the Naval Explosive Ordnance Disposal Technology Division, with funding provided by the DoD Physical Security Equipment Action Group (PSEAG).
Funding AgencyGrant Number
Naval Explosive Ordnance Disposal Technology DivisionUNSPECIFIED
Department of Defense (DoD) Physical Security Equipment Action Group (PSEAG)UNSPECIFIED
Subject Keywords:Reflector antennas; scanning antennas; submillimeter-wavelength imaging; terahertz radar; THz
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INSPEC Accession Number11328349
Issue or Number:6
Record Number:CaltechAUTHORS:20100701-094926697
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:18894
Deposited By: Tony Diaz
Deposited On:14 Jul 2010 16:35
Last Modified:09 Mar 2020 13:19

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