announcement

Share facts or photos of intriguing scientific phenomena.

Do Radar Jammers Work?

How Do We Really Know if Radar Jammers Work? Let's Find Out

Radar jammers are considered illegal in many countries due to their misuse. If you are wondering what these devices are and how they work, continue reading this story.
Aishwarya Nirmal
Last Updated: Mar 14, 2019
Radar, an acronym for RAdio Detection And Ranging, is an electronic instrument used to determine the range, altitude, direction, or speed of moving as well as fixed entities. Nowadays, a radar gun is commonly used in speed detectors by the traffic police to determine the speed of vehicles.
To avoid being detained by the police, many people use radar jammers that obstruct the working of these police detectors. However, of late, police detectors have started utilizing smarter technologies to overcome this problem.
The basic components of a radar are the transmitter, receiver, antenna, synchronizer, display, and switch duplexer. The transmitter generates the radio pulse to be transmitted. The antenna broadcasts it in the direction of the object to be detected. The radio wave that is transmitted is in phase when emitted, but disperses once it hits the target object.
Part of this scattered wave is reflected back, which is caught by the antenna and sent to the receiver. Since the reflected signal is weak, the receiver amplifies it and further calculations are done accordingly.
If the target object is moving, there is a slight change in the frequency of the reflected signal which indicates that the object is in motion. The switch duplexer controls the functioning of the antenna and connects it to the transmitter or the receiver, according to the requirement.
Radar Jammer and its Functions
The main objective of a radar jammer is to scramble the signals of the radar. A jammer is an instrument that reflects the incoming signal, or transmits its own electromagnetic wave signal at the same frequency as that of the radar detector's signal.
This may cause the detector's signal to distort, saturate with wrong information, or get jammed with an additional signal called noise. There are two types of jammers, passive and active.
Passive radar jammers reflect the incoming signal of a police radar gun with an additional FM chirp (a signal whose frequency increases and decreases with time), so as to confuse the radar gun. This theory works only if the radar detector is within a distance of three feet; beyond three feet it becomes weak and is unable to jam the radar gun.
Active jammers transmit their signal at the same frequency as the source. They come in two types―active radar jammers and active laser jammers. Active radar jammers send a signal matching the detected radar frequency, whereas active laser jammers emit light beams that blind the laser system. It scrambles the outgoing signal long enough to pass by undetected.
Active radar jammers are more effective on the X band (10.5 - 10.55 GHz; radar guns in this spectrum can take accurate readings of speed from a distance of 1/2 mile or less) and the K band (24.05 - 24.25 GHz; the radar can detect the speed from a range of 1/4 to 2 miles).
However, when the Ka band (34.2 - 35.2 GHz) radar detectors were included in police equipment, jammers became useless due to the wide frequency range.
Using radar jammers is prohibited in many states, as they operate on radio waves controlled by the FCC (Federal Communications Commission). But laser jammers use light and are not under the jurisdiction of the FCC, hence, may be allowed in some places. Radar jamming is considered a felony in many countries, and it's best not to fit one in your vehicle.