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Everything You Need to Know About Radar Detectors

Everything You Need to Know About Radar Detectors

Everything You Need to Know About Radar Detectors

Radar detectors have been a popular accessory for drivers for decades. These devices are designed to alert drivers when their vehicle is being targeted by police radar guns, giving them time to check their speed and slow down if necessary to avoid a speeding ticket. But how do radar detectors work and are they legal to use? Let’s take a closer look.

How Do Radar Detectors Work?

Police use radar guns that emit radio waves at a specific frequency to measure the speed of passing vehicles. Radar detectors are essentially radio receivers that are tuned to pick up on those same frequencies. When a radar detector senses a signal, it alerts the driver with visual and/or audible warnings.

There are several different bands of frequencies that police radar guns operate on:

  • X band: Oldest and least common, but still occasionally used. Prone to false alerts from things like automatic door openers.
  • K band: Widely used by police. Less prone to false alerts than X band.
  • Ka band: Newest technology used by police. Very difficult to detect in advance.
  • Laser: Used by police but not detectable by conventional radar detectors. Requires a separate laser detector or a radar detector with laser detection capabilities.

More advanced radar detectors can filter out many common sources of false alerts and offer features like GPS to remember and mute common false alert areas along your regular driving routes.

Are Radar Detectors Legal?

The legality of radar detectors varies by location. They are legal in most of the United States, with the exception of Virginia, Washington D.C., and on U.S. military bases. Radar detectors are also illegal in most of Canada.

Even where radar detectors are permitted, there may be restrictions on their use. For example, Minnesota and California prohibit mounting devices on the windshield that may obstruct the driver’s view.

Commercial vehicles over 10,000 pounds are also prohibited from using radar detectors nationwide in the U.S. under Federal Motor Carrier Safety Administration regulations.

It’s important to research and understand the specific laws in your area regarding radar detectors before purchasing or using one.

Choosing the Right Radar Detector

If you’ve determined that using a radar detector is legal in your area, the next step is choosing the right device for your needs and budget. There are many different radar detectors on the market with a wide range of features and price points.

Some key things to look for when shopping for radar detectors:

See Also

  • Type of detection: Does it detect X, K, and Ka bands? What about laser? More bands detected means more comprehensive protection.
  • Range: How far away can it detect radar signals? Longer range gives you more advanced warning.
  • Filtering and false alerts: Better detectors minimize annoying false alerts from things like automatic doors.
  • GPS: Allows the detector to remember common false alert areas and mute them on future passes. Some also include preloaded databases of red light and speed cameras.
  • Smartphone integration: Some detectors can link to your phone via Bluetooth for additional functionality.

Expect to spend anywhere from under $100 for a basic detector to $500+ for a high-end model with maximum range and features. Popular brands include Escort, Valentine One, Radenso, and Uniden.


Radar detectors can be a very useful tool for drivers looking to avoid costly speeding tickets. By understanding how they work, the laws around their use, and the key features to look for, you can find the right radar detector for your needs.

When shopping for radar detectors, stick to reputable brands and vendors. Poorly designed detectors can actually transmit their own signals that police can detect, getting you in more trouble than if you didn’t have one at all.

Used properly, a quality radar detector can pay for itself many times over in avoided tickets. Just remember, they are not a licence to speed everywhere with impunity. Always drive safely and responsibly.