Non-Planner GPS Receiving Antenna Navy STTR FY2005 Sol No.: Navy STTR FY2005 Topic No.: N05-T002 Topic Title: Non-Planner GPS Receiving Antenna Proposal No.: N054-002-0077 Firm: Spatial Digital Systems, Inc. 2350 Moberly Ct Thousand Oaks, California 91360 Contact: Donald Chang Phone: (805) 405-7689 Web Site: www.spatialdigital.com Abstract: It is desirable to have small aperture for a user, but with better antenna gain toward GPS satellites and discrimination against jammers at low elevations. SDS proposes a methodology which will utilize multiple high gain spot beams from a non-planer array providing many AJ links simultaneously between GPS satellites and the user. The multi-beam antenna not only provides connectivity but also ensures isolations and discriminations against interference at low elevation angles. We will use AJ performance of a GAS-1 antenna as a key reference for comparisons. Multiple beams will be implemented via digital beam forming (DBF) technology, which enable the capability of dynamically picking various sets of elements for different beams. Projected apertures will be utilized to identify various sets of array elements available to form different individual beams, each pointing to a specific GPS satellite or a jammer. As to rejecting the jamming signals, elements with maximum base-line will be chosen to discriminate against jamming signals with the best nulling widths. Many predetermined receive beam positions/directions will be used to cover the hemisphere. Element weights for a nonplaner array for a given beam direction are opimized to maximize the peak gain through cross correlation techniques. Benefits: The proposed non-planer array antennas will form multiple AJ beams, and enable user with multiple AJ links pointing to various GPS satellites and receiving their associated timing signals to derive the user position. The multibeam antennas not only provide connectivity but also ensure isolations and discriminations against interference at low elevation angles. Besides DoD, markets for the advanced geo-positioning systems may arise as an important means for air traffic management and civil communication. Interference has been identified as a challenge related to the use of GPS. Despite this, the technical feasibility of using augmented GPS as the only means of commercial navigation in the aircraft as well as the only navigation service provided by the Federal Aviation Administration (FAA) was confirmed as technically feasible. Efficient non planer GPS terminals may become applicable to many military, civil systems and to the commercial aircraft and airline industry. Return