Speed Radar Facts and Myths

Radar gun myths busted

If you are caught in the speed radar's crosshairs, here are some facts and fallacies to better educate you on the infamous (and dreaded) radar gun.

Radar gun on motorcycles
Differentiating fact from fallacy can help you better understand why the radar gun caught you in its sights.Photography by Dean Groover

Fallacy: Speed radar will pick up the fastest target.
Fact: It only picks up the target that "looks" largest to it. That is the target that reflects the most of its signal back to the gun.

Fallacy: Speed radar picks up the nearest target.
Fact: See above.

Fallacy: Speed radar picks up only approaching vehicles.
Fact: Speed radar picks up all metallic objects of sufficient size moving through its beam, which may be as wide as 24 degrees. (Laser guns have a much narrower beam and can pick out an individual motorcycle.) In fact, vehicles going away from the radar gun typically continue to give readings farther from the gun because their rear portions are more likely to be large, vertical, flat surfaces, which reflect microwaves most effectively.

Fallacy: Speed radar can get the precise speed from any vehicle that is close to it.
Fact: Besides the fact that a larger vehicle may be read even though a motorcycle is closer, radar can only accurately measure the speed of a vehicle that is directly approaching or retreating. If you pass the gun perpendicularly at 100 mph, at your closest point you will read almost zero, though it will increase if the gun tracks you.

Fallacy: A radar gun projects a narrow beam that permits the operator to precisely select his target.
Fact: This is true for speed laser guns, but not radar. The radar's beam is wide enough to get vehicles in all the lanes. This is particularly significant for motorcycles, since the speed of a retreating truck half a mile down the road may be mistaken as a motorcycle's velocity by the radar operator, who wasn't paying attention to it.