Different Types of Radar

The Federal Communications Commission has dictated that police radar must operate on specific frequency bands:

X-Band 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."

K-Band: 24.05 - 24.25 GHz

K-band, the most common type of police radar, 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 and so are more easily absorbed by water molecules in the air. 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 to 2 miles.

K-band guns also have what's known as "Instant-On" radar. This is basically a kill-switch option which keeps the transmitter in "hot standby" mode, ready to be activated by an officer when the target is within 200-300 yards. If it's been aimed at you, your speed has been measured by the time the detector alerts you. If it is being used to target vehicles ahead of you, your detector may provide a warning in time for you to adjust your speed.