Radar detectors were introduced in the early 1970's. The term radar detector originated from technologies that were used earlier to detect speed.

Now the question arises, "What is radar?" Radar is a system used to measure the speed and location of any object. This system consists of two important parts - a transmitter and a receiver. The radio transmitter causes voltage fluctuation by oscillating an electric current at a predefined frequency. This oscillation of the electric field generates electromagnetic energy. This electromagnetic energy propagates in the air as electromagnetic waves. A transmitter consists of an amplifier and an antenna. While the former increases the power of electromagnetic energy, the latter transits it into the air.

The basic function of radar is to determine its distance from the destined object. For this function, the radar device emits concerted radio waves to observe any echo. If any object comes in the way of the radio waves, then it can be easily detected by radar with the help of electromagnetic energy. Radio waves constantly travel in the air at the speed of light. The distance of the object from the radar is determined by observing the time taken by the radio waves to return.

For measuring the actual speed of any object, radar can be used with a fact called Doppler shift. When any moving object passes in front of the radar, its echo will reflect the signals of the radar. The time taken by the radio signals to return after striking the object, and the frequency with which they travel, gives the actual speed of that object. If an object is coming towards the radar, then the signals will come back in a shorter period of time. It will increase the frequency and tells the actual time in which an object will cross the radar. This process depends on how fast the frequency will change. Traffic police use radar in the form of a radar gun, which is either hand-held or vehicle mounted, to detect speeding vehicles.

A basic radar detector detects police radar with just a simple radio receiver. In contrast, detectors that are more sophisticated comprise of a basic receiver along with a radio transmitter. A jamming signal is produced via this transmitter. It blends the signal of the police radar gun with extra radio noise. Due to this, a perplexed echo signal is received by the police radar gun, and the exact speed-reading cannot be taken.

Light-sensitive panels are being used in modern detectors which detect the beams from police laser guns. Lidar is difficult to avoid due to its concentrated beam, so it is quite possible that by the time the detector is able to detect it, the vehicle is in the beam's sight already. For that, speeders also use a laser jammer. It works much like a radar jammer.

In conclusion, there are several systems available to detect radar, but none of these systems is a sure shot way to get protected against speed detectors. However, one thing that can be done to avoid speeding tickets is to 'slow down'.