wind a small RX i.e.: a field strength coil and LED indicator, or buy one of
them cheap 'bug detectors', stick on a gas filled WX balloon, get a hand
held radio or mobile phone, and place a RX next to the radio Mic, put your
radio on VOX and key from out side, by talking into the hand held, drag the
balloon round with long a string observing the bug detector as a led field
strength meter by viewing the LED barographs twinkling light, with a
binocular. Easier at night.