GPS Ground Station Antenna for Local Area Augmentation System, LAAS

Alfred R. Lopez

Abstract:	The requirements for a LAAS ground station are such that unusual antenna specifications need to be defined and implemented. For code tracking, the group delay variation over the coverage should be specified; this is not a typical antenna specification. For carrier-phase tracking, the phase center variation over the coverage should be specified; also not a typical antenna specification. The impulse response over the coverage should be such that any waveform degradation is within acceptable limits. Listed below are the key requirements for a near ideal GPS Ground Station Antenna. Hemispherical Coverage (down to 3...elevation) Right Hand Circular Polarization Over Entire Coverage 3 dB/Degree Cutoff at Horizon Sidelobes > 23 dB Down from Peak in Lower Hemisphere Point Phase Center Point Group-Delay Center A concept that incorporates some of these features was developed in 1996, U. S. Patent, 5,534,882 [1]. More recent developments have resulted in an antenna configuration that incorporates all of the desired features. This paper presents the basic concept disclosed in the issued patent and the additional attributes of the improved design. Such an antenna has been developed. It operates at the L1 and L2 frequencies. Measurements of breadboard and production prototype antennas have verified the performance.
Published in:	Proceedings of the 2000 National Technical Meeting of The Institute of Navigation January 26 - 28, 2000 Pacific Hotel Disneyland Anaheim, CA
Pages:	738 - 742
Cite this article:	Lopez, Alfred R., "GPS Ground Station Antenna for Local Area Augmentation System, LAAS," Proceedings of the 2000 National Technical Meeting of The Institute of Navigation, Anaheim, CA, January 2000, pp. 738-742.
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