I recently purchased a small hand held magnetic and electric field tester to assist me with turning an old CPU into a low-power radio emitter. The sensor reports very steady and high levels of magnetic field and electric field whenever the microwave oven in the other room is cooking. As microwaves have large wavelengths, I assume they could not escape the oven. What, then, is my sensor detecting? Or is my assumption wrong?
The sensor is uncalibrated. With the exception of an air ionizer, no other household device comes close to the readings.