Some basics of electromagnetic and information energy are discussed. Radio wave transfer of information requires modulation in a transmitter and detection, also called demodulation, in a receiver. Modulation and demodulation are based on non linearity. An essential overview is presented. Non linearity in the body may convert radio signal power into a low frequency current density able to cause (bio)chemical effects. The hypotheses of a beat frequency for which the conversion efficiency is assessed, deserves further investigation. Experiments to reveal a non linear response should include detection of an extremely low frequency beat frequency in the microwave range.