Jeff Liebermann wrote in
:

On Tue, 15 Feb 2011 08:32:11 -0800 (PST),
" wrote:

This type of product is advertised almost everywhere that it helps you
avoid tickets etc.

Episode 18: Beat the Radar Detector
http://mythbustersresults.com/episode18

I imagine that it must transmit a signal on the
same freq. as the radar gun at the moment it receives the police
transmission.

You have a good imagination. The illegal ones are essentially radar
jammers. That's not as easy as it sounds as getting the timing just
right so that it coincides with a radar *PULSE* is tricky. Most
handheld radars now work on several bands simultaneously, making a
universal radar jammer somewhat difficult and expensive to produce.

How are the HANDHELD radar guns multi-band?
they would have to have multiple Gunn oscillators,too.

And more than one feed horn.(antenna)
Most that I've seen on police cars are pretty small units.

AFAIK,most radar guns are Doppler,and the receiver reads the strongest
signal it receives,so transmitting a signal from your "jammer" overpowers
the reflected radargun signal.That jammer signal has to be near in freq
to the gun's signal,or it will be rejected,because it would indicate a
higher speed than the gun will measure or considers reasonable.Then the
speed gun would light it's "interference" indicator.


do you have any information on or links to these multi-band radar speed
guns?

--
Jim Yanik
jyanik
at
localnet
dot com