Welcome, from sunny Australia!

Police Radar Jammer

Okay, I have to say from the start that this is probably a pretty crap idea, but it may work. The current plan for most drivers that speed is to either try to see the radar before they get 'zapped' or use a detector to get prior warning of the radar gun before they get 'zapped'.
Both these plans are pretty dodgy and don't work very well for a couple of reasons; The Police are really good at the job and are plenty smart enough to hide so you can't see them until too late, and again the Police are plenty smart not to wave the gun around to give your radar detector prior warning, until they point it right at your car to get a reading and then it's too late. You're better off in traffic though as they have to run the gun often to test people and so you can often get prior warning that way. But of course not all places allow radar detectors, so you're back to the unreliable method #1.

* Note that I do not condone speeding at all, this is merely a 'thought' device that I came up with that if you want to build and test yourself go right ahead. You'll know if it doesn't work because you'll get a ticket, so go right ahead. ;)

There's another few options to try to defeat the radar -
- Use a good jammer that picks up the signal of the radar and returns the signal 180° out of phase so that there is very little reflected signal. The military with billions of dollars of research have enough trouble getting this to work, so I didn't even bother trying to sort this out ...
- Make a pure jammer that creates a loud signal in the radar band to effectively jam the gun. Might work, but it's like a big neon sign to the Police that says "please give me a ticket" as they'll pick it up very quickly indeed.
- Make a jammer that sends a constant signal that the gun picks up the car doing a lower speed. Again the Police can usually pick this up and you're in deep trouble if caught with one. They're illegal everywhere. (though I do like the idea)
- Deliberately send a good signal back to the gun, but with it showing a very high speed, much higher than the real speed of the car. This can often happen with some guns when pick up a reflection off the radiator fan, etc.

I settled on the last option, and came up with the following idea -
Make a gadget that the incoming radar signals bounces off the makes the returning signal go back a few hundred KPH faster, thus making the car look like it's going about 300kph faster than what it really is.
To do this, I reckon that a simple rotating drum with a couple of metal reflectors on it would do the trick. The cross-section would look like this -

The reflectors sit on a simple set of supporting arms that attach to a central axle that sits right in the middle of a 8" diameter drum that rotates inside a slightly larger stationary drum.
All the parts, except for the reflectors, are made from plastic to make them radar transparent.
If you suspended the shaft in some bearings at the end of the outer drum and attached it to a small electric motor that spun the inner drum up to 10,000rpm, (easy to do, as there's no aerodynamic drag, just a little bearing friction) that the average speed of the rotating reflectors would be about 287kph, as the radar wold see them.
The reflectors would be a simple 90° angled piece of metal, as a 90° reflector always bounces the incoming signal straight back to the source. Most of a car isn't a very good reflector, so by deliberately sending a good signal back the radar gun would most likely use that one as the main reading.
Say you're doing 120kph in a 100kph zone and you get zapped by a radar gun and have this gadget running - Instead of the gun showing you at 120kph it'll show more like 407kph, which the operator will most likely ignore and move to the next target.
The only tough thing is to physically hide the tube in the front of the car .... Naturally it'd work better the longer and wider it is, to allow for bigger reflectors, etc, but unfortunately in most cars there's not a lot of room behind the bumper-bar.

But in any case, the Police are heading more towards laser guns, and so this gadget is no good with those ....   ;)

On to the -
- Geothermal power plant
- Laptop computer electronic circuit simulator
- Anti-aircraft missile system
- Horizontally opposed diesel aircraft engine
- Different electric car
- Listening spy device
- Super cooler device
- Land speed record car contender
- Water speed record contender

Back to the Index page

Page & contents where applicable © Bill Sherwood