>/k/ can't even google nowadays
Dark times ahead.
en.wikipedia.org/wiki/High-frequency_direction_finding
en.wikipedia.org/wiki/Radio_direction_finder
Basically you take two directional antenna loops and set them up in a 90° angle to each other. Then you take them both and hook them up to one axis on an osciloscope each.
When a signal comes from a certain direction it will increase the measured intensity of each axis seperately on the osciloscope, creating a line that directly goes from the target through the center to the opposite side. Now hook up a normal antenna. The shift in phase between this antenna and the other two can be used to eliminate the false direction on the screen and get essentially an "anarchist in this direction" device.
Put it on your car (locating the source of a signal is not illegal, you are not broadcadting anything) and keep driving towards the signal.
This is WWI tech, for fucks sake. /k/ is embarassing sometimes.