Advanced Anti-Jam GPS Antenna Design Concepts

The objective of the Advanced Anti-jam Design Techniques effort is to make a controlled Radiation Pattern Antenna (CRPA) have more elements without increasing the size, or make it the same antenna (i.e., same number of elements) smaller. The moreradiating elements that are available in a CRPA design, the more response nulls can be directed towards jammers. The inherent design problem that needs to be overcome is that the Objective GPS antenna requires closer element spacing and as a result,traditional CRPA antenna performance suffers from the electromagnetic effects of close element spacing. The cause of the performance shortfall is excessive mutual coupling, which causes the nulling algorithms to hunt longer or settle more slowly on asolution. Also, traditional CRPA antennas have insufficient pattern slope, which adversely effect antenna gain in the desired directions of reception. This effort will result in smaller antennas that have enhanced beam-forming and null-steeringcapabilities. Although this performance is of particular benefit in military applications, to suppress jammer signals, the approach can also be used to suppress other noise sources and signal multi-path. Therefore these antennas are valuable to theprivate sector as well as to the military.