Antenna for GPS CCM Improvement (SPC Proposal 5179)

Antijam protection for GPS receivers can be provided in a cost-effective way by restricting the antenna reception to the upper hemisphere only, thereby eliminating the majority of intentional and unintentional jamming sources in either a war- fighting context or terrorist attack scenario. Competing schemes using null- steering antennas or receiver/processor improvements are not cost effective and do not offer good performance capability against multiple noise jammers emitting random wideband signals from multiple geographic locations. The proposed System Planning Corporation (SPC) antenna approach would be a Joint Standoff Weapon (JSOW) Preplanned Product Improvement (P31) candidate. It would keep available the desired circular polarization coverage over an adaptable sector of the upper hemisphere (excluding the horizon) and significantly reduce unintentional coverage of the lower hemisphere provided by conventional antennas. This would be achieved by providing an adaptable beamwidth for the upper hemisphere and significantly reducing sidelobes/backlobes in the lower hemisphere. Novel techniques for electronic control of the beamwidth and reduction of missile excitation using contoured corrugated surfaces near the aperture are the key proposed enabling approaches. Improvements in jammer-to-signal performance of greater than 20 dB are expected for horizon and lower hemisphere jammer locations.