IIRC I think there was a telephone system with giant magnetic coils that went a quarter mile, but maybe I read a blog wrong or something. In any case it wouldn

IIRC I think there was a telephone system with giant magnetic coils that went a quarter mile, but maybe I read a blog wrong or something. In any case it wouldn't be as portable and would make you rather easy to detect I would imagine, if you wanted to cover a large area.