After getting the quadcopter to fly in loiter and auto missions with confidence, it was decided to use the quadcopter for measuring RF signal propagation. This measurement was done with a transmitter on one side of a 13m high human-made berm. Flying a vertical path up to 50m on the far side measuring the diffraction of the continuous wave signal at 400MHz. Below is a video with the payload strapped to the quadcopter, note that the antenna (yellow block) was exchanged for a small stub antenna during the actual measurement. The measurement was done using my RS232 spectrum analyser logging onto a Raspberry Pi. The effect of the quadcopter on the antenna pattern was ignored, and the measured data were treated as relative. The measured data can be seen in the featured image and resembles a diffraction pattern. This pattern has been verified against some prediction code of a colleague. As a first test, this proved very successful as a proof of concept and was hereafter named fEMu (flying Electromagnetic Metrology unit).