Advanced Wheel/Rail Interaction Force Measurement System

Not Available A novel anti-jam GPS antenna concept is proposed that is an alternative to the complex and expensive Controlled Reception Pattern Antenna (CRPA) currently in use. This approach, called the L-CRPA, can utilize installation foot prints as small as a Fixed Reception Pattern Antenna (FRPA) and provide three modes of operation. Mode-1 provides a typical broad-coverage FRPA pattern for situations when no jamming is present. Mode-2 and Mode-3 provide two anti-jam patterns. Mose-2 provides a steerable null in azimuth with potentially greater than 25 dB J/S. Mode -3 provides enhanced elevation pattern rolloff at all azimuth angles, for situations when a large number of jammers are present at many different azimuth angels. The antenna electronics required to produce these modes is simple and inexpensive. Passive pattern control technologies are also offered to provide additional anti-jam performance. The development of L-CRPA offers a cost effective alternative to CRPA hardware and the potential for a significant enhancement to in-situ FRPA systems.