How Radar and Radar Detectors Work
How Police Radar Works
A typical radar gun consists of a radio wave transmitter combined with a radio wave receiver. The gun shoots out radio waves at a specific frequency. The radio waves travel through the air bouncing off objects they encounter. Some of these reflected waves will make it back to the radar gun. The waves that reflect off an object which is moving undergo a Doppler Shift. This Doppler Shift causes a change in the frequency of the radio wave. The radar gun uses this change in frequency to calculate speed of the moving vehicle. The good thing about a radar beam is that it is very wide and bounces around quite a bit.
How Radar Detectors Work
A radar detector is a radio receiver similar in nature to the radio antenna on cars used to pick up radio stations, but instead it is tuned to the specific frequencies radar guns use. A radar detector’s job, however, is to pick up and alert the driver to police radar before the reflected signal is strong enough to make it back to the officer and give them a speed reading. Detection of weak signals is very important for radar detectors and they use a horn antenna design to accomplish this. The detector creates internal signals and then compares these to the signals picked up by its horn.