Analysis of LAAS Integrated Multipath Limiting Antennas Using High-Fidelity Electromagnetic Models

Daniel N. Aloi, Sai Kiran

Abstract:	The multipath limiting antenna array exists in a 14- element version and a 16-element version. The basic radiating element of the multipath limiting antenna is a quarter wavelength dipole cup. Each of the dipole cups are excited at four distinct points along its circumference, and a sophisticated feed network produces the correct amplitude and phase excitations for each radiating element to generate the desired reception gain pattern. The multipath limiting antenna was designed to mitigate ground-induced multipath reflections by shaping its radiation pattern to produce a desire-to-undesired gain ratio in excess of 30.0 dB. In addition, the large vertical aperture of the antenna produces phase center variations and group delay variations as a function of elevation angle. This paper utilizes a validated electromagnetic model of the 14-element multipath limiting antenna to assess the impact on the desired-to-undesired gain ratio and the phase center variation in the case where one of the radiating elements goes bad. The antenna response is investigated when 1-of-4, 2-of-4, 3-of-4, and 4-of-4 feed points go bad for the failed element. The results of this study show that both elevation and azimuth dependent variations in desired-to-undesired gain ratio and phase center variation can occur to different degrees for a particular failed element. This error is also dependent on the number of feed points that are bad within the failed element.
Published in:	Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004) September 21 - 24, 2004 Long Beach Convention Center Long Beach, CA
Pages:	2303 - 2315
Cite this article:	Aloi, Daniel N., Kiran, Sai, "Analysis of LAAS Integrated Multipath Limiting Antennas Using High-Fidelity Electromagnetic Models," Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004), Long Beach, CA, September 2004, pp. 2303-2315.
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