LAAS Reference Antennas … Key Siting Considerations

Alfred R. Lopez

Abstract:	At the ION Annual Meeting, 2003, a paper [1] was presented, which indicated that lateral multipath was a key issue in the overall performance of the LAAS reference antennas at an airport environment. This paper considers two basic types of lateral multipath objects, fixed and transient, that can significantly affect the LAAS performance. The fixed object is the vertical wall (hangars, terminal buildings) that can cause reflection/diffraction multipath from a vertical wall. The transient objects are an aircraft tailfin and an aircraft fuselage. These transient objects have convex surfaces that generate relatively large specular reflection zones with multipath-to-direct signal ratios that can cause significant multipath error. The goal of this paper is to establish the sensitive zones for these objects. The minimum distance between the reference antenna and the reflecting object will be determined such that the peak multipath error does not exceed a predetermined value. The basic multipath model described in the above referenced paper will be used to quantify the multipath error. In addition, a satellite motion-averaging factor will be considered. The relative motion of the satellite with respect to the earth is such that, in some cases, the multipath interference frequency is well beyond the pass bands of the code delay-lock-loop and 100-second-average filters, and substantial suppression of multipath error is achieved.
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:	335 - 343
Cite this article:	Lopez, Alfred R., "LAAS Reference Antennas … Key Siting Considerations," 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. 335-343.
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