Constructive interference of microwaves is the most likely candidate I think. Each beam would be essentially harmless, but at their intersection you’d have a ba

Constructive interference of microwaves is the most likely candidate I think. Each beam would be essentially harmless, but at their intersection you’d have a bad time. This could be used by adversaries to power bugs as you reference in another post, but also by friendlies sweeping for bugs. As a bonus the emitters could be compact compared to some monstrous speaker systems, and probably mobile.