Artificial Magnetic Conductor Technology Reduces Size and Weight for Precision GPS Antennas

William E. McKinzie III, Ralph Hurtado, and William Klimczak

Abstract:	Methods to reduce mulitpath for precision GPS antennas have included flat conductive groundplanes, parasitic groundplane treatments, and reactive groundplane treatments. Of these, the choke-ring reactive groundplane has been widely used and adopted as a defacto standard. While choke rings do deliver good electrical performance, they have three significant drawbacks; size, weight, and cost. In this paper, we present a relatively thin, lightweight, and inexpensive alternative ground plane, called an Artificial Magnetic Conductor (AMC). This new AMC technology is realized with printed circuit technology, and it simulates a magnetic conductor over a limited range of frequencies. It is a type of high-impedance surface, which has a surface wave bandgap for TE and TM modes. This ground plane is designed to suppress surface currents, thereby reducing edge diffraction, ground bounce effects, and forcing the far field pattern to roll off more rapidly near the horizon. An AMC ground plane can replace a conventional milled choke ring of the same diameter with at least a 6x weight reduction and at least a 5x reduction in thickness. Measured gain patterns show comparable performance to a choke ring in terms of pattern roll-off near the horizon, front-to-back ratio, and cross-pol rejection below the horizon.
Published in:	Proceedings of the 2002 National Technical Meeting of The Institute of Navigation January 28 - 30, 2002 The Catamaran Resort Hotel San Diego, CA
Pages:	448 - 459
Cite this article:	McKinzie, William E., III, Hurtado, Ralph, Klimczak, William, "Artificial Magnetic Conductor Technology Reduces Size and Weight for Precision GPS Antennas," Proceedings of the 2002 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2002, pp. 448-459.
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