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Radar Information

A radar speed gun is a Doppler radar unit that may be hand-held, vehicle-mounted or static.

About Radars

How does a radar work?

It measures the speed of the objects at which it is pointed by detecting a change in frequency of the returned radar signal caused by the Doppler effect, whereby the frequency of the returned signal is increased in proportion to the object’s speed of approach if the object is approaching, and lowered if the object is receding.

What types of radar bands exist?

Law enforcement officers will typically use one of the following radar bands for determining your speed

  • K-Band: The most frequently used radar frequency band: 24.05 – 24.25 GHz. K-band made its appearance in 1978. The first K-band hand-held radar guns could only be used from a stationary position. Later, a “pulsed” version was introduced that could be used from a stationary or moving vehicle.K-band radar waves have a relatively small wavelength. At the power level found in police radar guns, K-band has an effective clocking range of about 1/4 mile. Depending upon terrain (around a corner, over a hill, etc.), K-band waves can be detected from a range of 1/4 mile to 2 miles.
  • KA-Band: In 1987 the FCC allocated a frequency on yet another band, Ka, for police radar use. Ka-Band incorporates Ka-Band, Ka Wide-Band, and Ka Super Wide-Band. With Ka came the introduction of photo radar (also known as “photo-cop”). The photo-cop system works at 34.3 GHz and combines a Ka-band radar gun with an automated camera (see Photo Radar below).The FCC later expanded Ka-band radar use to a range of 34.2 to 35.2 GHz. This became known as Ka Wide-Band.The introduction of the “stalker” radar gun raised the stakes in the detection game. Unlike all previous guns, the Stalker can be FCC licensed for any frequency in the Ka-band between 33.4 GHz to 36.0 GHz, and so cannot be picked up by detectors designed only for X, K, and photo radar. Stalker guns are being used in more than half the country.
  • KU-Band: Ku-band radar ranges between 12 and 18 GHz. It is used primarily for satellite communications, in both aerospace and broadcasting. It is used primarily in Europe and not seen much in America. In the radar enforcement realm, Ku is set at 13.45 GHz by the FCC and has only recently been introduced to the U.S. for speed detection.
  • X-Band: The first frequency band allocated for police radar: 10.5 – 10.55 GHz. Dating from the 1950s, X-band radar is the easiest to detect because of its lower frequency and higher power output. Depending on terrain, temperature and humidity, X-band radar can be detected from a distance of 2 to 4 miles, yet it can only take accurate readings of speed from a distance of 1/2 mile or less.Unfortunately, police radar is not the only source of X-band signals. Garage door openers, microwave intrusion alarms, microwave towers, and other high-tech equipment can fool a radar detector into giving off an X-band alert. Filters and redundant sampling are used to combat this “falsing.”

Radar Jammers

Radar jammers work on the principle of interfering with or overwhelming the doppler shift that occurs from the reflected radar beam that police RADAR guns require to obtain a vehicles speed.

Unlike police laser (at least in most states), police RADAR can not be legally jammed, in fact, any attempt to do so (whether one is successful or not, most active radar jammers are not) is a federal offense and violates FCC regulations. Simply put: you can be sent to jail if caught using a radar jammer.

Radar Calculations


Radar Measured Speed = True Speed x cos(angle)

Under Creative Commons License


 Radar Detector Legality Map


 Radar Detectors

What is a radar detector?

A radar detector is an electronic device used by motorists to detect if their speed is being monitored by police or law enforcement using a radar gun. Most radar detectors are used so the driver can reduce the car’s speed before being ticketed for speeding.

How do radar detectors work?

Radar detectors make make usage of a Superheterodyne Receiver to pick up electromagnetic emissions that are sent from the radar gun. When these emissions are picked up, an alert in the form of an audible alarm will will notify the driver. Despite advancements in modern radar detectors, false alarms can occur due to the wide array of devices that also use radar waves such as automatic doors and automotive backup sensors.

Are radar detectors legal?

Radar detector legality varies between states and countries. We’ve made a map listing the legality of radar detectors in the United States below.

  • Green: Legal
  •  Red: Illegal
  • Yellow: Questionable



 Under Creative Commons License
Via RockyMountainRadar

 Received a citation due to a police radar?

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