Earlier quoted context omitted.
Not knowing how to find them, is a load of crap. You can certainly find them, it just takes expensive equipment and time.
If it were me, the antenna would be a few hundred feet away from the equipment. And the antenna wouldn’t be anything like an antenna, just something that looks like a lawn-chair. And I’d move it every day or two. And definitely not run it 24h!!! Could still be found, but good luck.
So that then means a super-thick faraday cage around the actual device, and probably somewhat noteworthy power consumption (a battery certainly wouldn't be enough).