Scott in Aztlan wrote
Ted Edwards wrote:

Suppose you were participating in a search for a hidden radio
transmitter, only
instead of the usual radio receiver with a directional antenna you have
a
receiver with an omnidirectional antenna and a GPS receiver.

What is the reason for the constraint?

The radio receiver in question has a built-in omnidirectional antenna and
no
jack for an external antenna.


Turn the whole radio/built-in antenna into a directional antenna by mounting
it 1/4 wavelength infront of a metal surface.

The metal surface can be tin foil over a piece of cardboard.

Rotate the radio and metal surface to find the direction of the signal.

Calibrate it with a known transmitter location first before you go hunting
for an unknown transmitter.