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Focal-Plane Multibeam Dual-Band Dielectric Lens for Ka-Band

Cruz, Catarina C. ; Costa, J.R. ; Fernandes, C. A. ; Matos, S.A.

IEEE Antennas and Wireless Propagation Letters Vol. 16, Nº 1, pp. 432 - 436, January, 2017.

ISSN (print): 1536-1225
ISSN (online): 1536-1225

Journal Impact Factor: 1,312 (in 2008)

Digital Object Identifier: 10.1109/lawp.2016.2582263

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Abstract
A shaped double-shell dielectric lens is evaluated as a primary feed for a multibeam single-reflector system operating in the satellite uplink and downlink Ka-bands, complying with gain and edge-of-coverage (EoC) directivity requirements. An assembly of dual-band printed feeds is integrated at the base of a single lens, each feed producing a virtual focus far behind the lens base and coincident with the reflector focal arch. The used double-shell lens approach, instead of a single-material lens, allows an extra degree of freedom to accommodate an aberration mitigation condition. This primary feed system is proposed as a low-complexity solution to enable fitting more beams per solid angle than conventional single-feed-per-beam systems based on a cluster of focal-plane horns. A proof-of-concept lens prototype with 87mm diameter and 62 mm height, fed by a linear arrangement of five dual-band printed feeds, was fabricated and tested at the Ka-band. The lens measured radiation patterns were post-processed to evaluate the combined performance of the lens with an offset F/D = 1 reflector system designed for 45 dBi EoC directivity. It is shown that it duplicates the reflector aperture efficiency compared to horn-fed systems with same feed separation.