What makes the STi undetectable?

**SuperSalad** · 03-20-2008, 02:52 AM

I have always wondered this question and was hoping one of you would know the answer. It seems that maybe if it was simple that all other RD manufacturers would follow suit.

My best guess is that the STi has a better outter casing which doesn't cause anything to emit from it.

-SuperSalad

**dpatel01** · 03-20-2008, 03:29 AM

Originally Posted by MEM-TEK

A while back, Jimbonzzz labeled a photo showing all of the internal electronics within the STi's dual horn antenna. The STi has three voltage controlled oscillators on approximately 6.5, 13 and 16GHz. Bel made the STi stealth by using dual radar horns coupled with low pass, band pass and high pass filters. Radar absorbing foam is also used to create a RF seal between the top and bottom halves of the portion of the horn assembly which contains the local oscillator board. Overall it is a very complex design.

found here: http://www.radardetector.net/viewtopic.php?t=30416

**jimbonzzz** · 03-20-2008, 05:57 AM

The #1 thing that makes the STI undetectable is the use of LNA's (Low Noise Amplifiers) in the front end. These provide high reverse isolation, letting signals in, but keeping signals from leaking out.

What little leakage the LNA's don't take care of is eliminated through the use of waveguide and microstrip filtering, and other steps.

One other thing is that the STi uses separate antennas and mixers for X-Band and K/Ka band. This also might allow them to filter more effectively.

**SuperSalad** · 03-20-2008, 09:06 AM

Do you know why other people don't start doing this?

**<<JAZZY>>** · 03-20-2008, 09:09 AM

Originally Posted by SuperSalad

Do you know why other people don't start doing this?

They either don't care because radar detectors are only illegal in Virginia and Washington D.C. or there are patents in place that prevent others from using the same method. It's great to have a stealth detector if you live in those two places or if you are a big truck driver in the U.S. but it is not necessary otherwise. Also, even if a cop doesn't detect your Bel STi, all he has to do is shoot you with instant-on radar and watch for brake lights to see if you have a detector.

**jdong** · 03-20-2008, 09:43 AM

Originally Posted by SuperSalad

Do you know why other people don't start doing this?

It sounds like a lot of work and requires complete redesigning of the entire detector platform and likely also limits what other kinds of modifications/features they can pack in.

All that will also raise the price of the detector, and for those driving in areas where detectors are legal (i.e. like 95% of the USA), it's not worth it for the manufacturer or consumer.