I recently found out a basic analog am fm radio can be used to scan for microwave frequencies.
I did a basic test at home with good results. I turned on radio to am with no signal static.
What your listening for is a change in noise. First, i held it to the cell phone and could hear a change.
Second, i tried it with the TV remote control and herd a different noise. I even put the radio in a metal box and was surprised to still hear the difference when tested.
Third, This last test concerned me the most. I turned on the microwave oven in the house and herd a 3rd and completely different noise when testing the home microwave oven. I also left the room to measure behind the wall and could hear still hear it and sorta get an idea of the drop off ratio. The reason for the concern is I've been hearing that 3rd noise off and on in my room with out using a microwave oven.
These radios are inexpensive and the batteries last a long time. Now I'm trying to record data.