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