The Radiobird looks like a Theremin and it also has to be played in a alike way. But the Radiobird is something different and it is way more simple than a Theremin. It is nothing more but a radio with a feedbackloop from the output back to the input of the radios amplifier. This feedbackloop is normaly open and the two open ends of the circuit are connected to the two antennas. The instrument is played by touching the two antennas. The conductance of the human skin acts as connector and closes the feedback loop.