Complex sentence: The radar uses the Doppler shift theory in order to pick up moving targets from long range (which the military calls a high stand off capability) Any object of sufficient size (vehicle) and density will show up on the radar.
Split into simpler sentences: The radar uses the Doppler shift theory in order to pick up moving targets. IT's range allows it to look from a long range (which the military calls a high stand off capability) Any objects of sufficient size (vehicle) and density that are moving will show up on the radar.