Radar from Behind: The Real Story
Does a rear antenna make a difference?
By Jake Hand
Last updated: 2020
Judging from all the Internet chatter, it would appear that police have unleashed a new doomsday weapon: a super-radar that can sneak up from behind and blast you without warning. The only defense, say these breathless missives, is a radar detector that incorporates a rearward-facing antenna. Like any good rumor this one contains just enough truth to lend it some credibility. But there's more to the story.
The best rear detection range we've seen by a model without a rear-facing antenna was from the Escort Redline. It reliably detected radar when it was still 1.25 miles behind us.
During another test the Redline alerted to Ka-band radar 4.1 miles behind us as we followed an 18-wheeler. Baffled by the extraordinary range, eventually we deduced that the polished-aluminum trailer doors were acting as a giant microwave reflector. When we dropped back a bit, the amplification effect vanished.
When we tested the Valentine One against the Escort Redline, the V1 had about four times the range on radar coming from behind. Two thousand feet would be plenty of range, given the limitations on radar when used to clock vehicles in front of the cruiser.
And pointing one antenna backward does have a downside. During a 750-mile road test a V1 alerted to X-band radar on cellphone towers from up to 15 miles away. After passing one, the Valentine alerted again for another 15 miles when the rear antenna spotted it. We noticed the same behavior in the Escort Max 360, a newer windshield-mounted detector with a rear-facing second antenna.
Radar in back is harder to spot, but that doesn't mean detectors with a rear antenna are the only defense. A sensitive radar detector can pick up radar coming from behind when the signal reflects from an object ahead—a speed limit sign is big enough—and reflects back into the antenna, setting it off.
Radar from behind can be a threat, but it's nothing to lose much sleep over. For all but the very unlucky, any detector with good range will see it coming in plenty of time.