Hi all,
I had a good look at a speed detector on a police car the other day.
The unit said it operates on 24 Ghz. (not 2.4Gig but 24Gig)
My knowledge of frequencies thus leads me to believe that the signal would be extremely narrow, and even if one did make a speed camera detector, the moment it detects the signal, it's probably too late, as the copper is already pointing the gun at you.
Do you concur?
Just because it's got a 12.5mm wavelength doesn't mean it's got a narrow beamwidth, though you can make a narrow beam with a smaller antenna if you use a higher frequency. If the unit you saw was fixed and not hand-held, it'd need at least a 45 degree beamwidth, since it's not steerable, and would have to cover 20-ish degrees left and right.
Whether handheld or car-mounted, it's probably only got a frontal dimension of a few cm (how big was it, 5cm?), which means the antenna is not likely to have much forward gain, maybe 2-3x - which agrees with a beamwidth in the range of 20-50 degrees.
Just my opinion...
Clifford Heath.
In the UK most traps are laser, which is even narrower beam! For radar, as long as your detector is twice as sensitive as theirs you should get a warning before they get a readable return pulse, but radar is used for all sorts of things, in the UK they are often used on temporary traffic lights and fixed non reporting speed warning signs - so you could be getting lots of false alarms.
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