The key to Patriot's Radar system is its ability to transmit and receive pulses barely longer then single cycles at the transmit frequency. The first waveform shown here is a pulse generated by an earlier Patriot Design, based on "off the shelf" antenna technology. The waveform on the bottom was produced and received by Patriot's current Design. The current Patriot antenna system produces a pulse at the desired frequency with little leading or trailing noise. The Patriot antenna system provides many advantages over pulse-based systems. Patriot originally developed the impulse radar system to allow time domain processing in Patriot's GPR systems. Because the impulse is extremely short (3 nanoseconds), the time to return can be used to gauge the distance traveled by the pulse. Furthermore, the transmit and receive antenna's are very directional, eliminating much of the multipath components of the return signal. The short pulse combined with the directional transmit and receive to provide us with a number of important advantages: - Very low average power during transmission - Low interference from other transmitters - Transmission invisible to conventional receivers - High bandwidth digital data transmission possible - Difficult detection by other impulse receivers -106-