A Dual-Stacked Reflector Antenna that Produces Equal Strength Circular Polarized L-Band Signals Everywhere on Earth for GPS Satellite Applications

Yong U. Kim, Frank M. Czopek

Abstract:	Current GPS satellites use an L-band array antenna consisting of 12 helix radiating elements to produce an equal strength signal independent of geo-location. The 12 helix elements are fed by a complex feed network which imposes design challenges and incurs high cost. This paper proposes a simple, low cost, antenna as an alternative to the existing L-band helix array antenna. The proposed reflector antenna utilizes dual-stacked dishes and a single, center-fed, self-supporting, Left Hand Circular Polarization (LHCP) backfire monofilar helix feed to produce the Right Hand Circular Polarization (RHCP) Mshaped beam. Analysis shows this reflector antenna design approach can provide similar or better performance than the existing multi-element array antenna over the GPS L-band (encompassing L1, L2, L3, and L5) frequencies with regard to beam shape, gain, and axial ratio. The measured antenna patterns from a 1/3-scale prototype antenna have shown an excellent M-shaped beam forming capability over the required frequency band, thus confirming the viability and validity of the design.
Published in:	Proceedings of the 21st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2008) September 16 - 19, 2008 Savannah International Convention Center Savannah, GA
Pages:	2740 - 2746
Cite this article:	Kim, Yong U., Czopek, Frank M., "A Dual-Stacked Reflector Antenna that Produces Equal Strength Circular Polarized L-Band Signals Everywhere on Earth for GPS Satellite Applications," Proceedings of the 21st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2008), Savannah, GA, September 2008, pp. 2740-2746.
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