Grant Erwin wrote:

Don't like cellphones on freeways? Build a simple jammer and nuke 'em
with about 30 focussed watts of power so they lose lock, drop signal,
and hang up. Wait until they redial and blast 'em again. Just don't aim
it at your crotch and pull the trigger, and don't aim it at any overhead
aircraft .. :-)

GWE
once offered $$$ to design and build one but declined after some reflection


A spark gap coupled to a tuned tank ckt. on the cellphone freqs. would
work fine. Put a series resonant ckt in the hot wire of your ignition
coil.

John