Jammers are highly illegal and will be confiscated if discovered, expect a stiff fine. This is a new device, which is really a scanner on the police radio band. It takes advantage of a signal transmitted by the patrol cars in some states as part of their dispatch system. The signal carries for about three miles, and the Chip's Detector will alert you if you are within that range of a highway patrol unit. It also allows scanning of police radio channels.
Radar is a basically accurate instrument, when used properly, it can be deadly.
As I have said before instant on radar is impossible to avoid when there is no other traffic around, regardless of a detector. The only thing that comes close is a Radar Jammer, which will most likely not serve you well unless it is WELL hidden. It is basically a stopwatch used to time your movement between two point of which the interval distance is known. Instant on radar defense. The only real defense for instant on radar is traffic.