Radar detects personnel (and larger) motion. Radar penetrates foliage and is well suited to air-deployment where the sensors may bury in grass, brush otherwise become obstructed.  Radar is range-gated, accepting motion within the factory set 40’ range bubble and rejecting signals from outside 40’ making detections more reliable.  Factory adjustable Doppler passband accepts target speeds within 0.1 to 40 m/s and filters out unwanted signal source velocities outside that band.  The radar has a very sensitive wideband receiver and has special requirements for system noise reduction.  The antenna is omni-directional.  Larger, directional antennas are available.