Dual-Band Quadrifilar Helix Antenna
December 2002
David Lamensdorf, The MITRE Corporation
ABSTRACT
Resonant quadrifilar helix antennas are widely used on hand-held receivers for GPS (Global Positioning System) and for some mobile communication systems. The significant advantages of this type of antenna include its relatively compact size and its cartioid shaped pattern with excellent right-hand circular polarization coverage and high axial ratio over most of the field of view. Since it is a resonant antenna, its dimensions are chosen to provide optimal performance for one frequency band. Several techniques have been described in publications that would extend this antenna's capability to two frequency bands (L1 and L2 for GPS applications). Each of these techniques has some limitations with respect to size and/or performance. A technique is described here that provides the same performance in two separate frequency bands and has no impact upon the overall size of the helix antenna.
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