Evidence for microwave-induced acoustical resonances in biological material

Pulse bursts of microwave energy were used to stimulate resonant-type acoustical response in a rectangular muscle-equivalent model and in a spherical brain-equivalent model. The rectangular model was irradiated using a military radar transmitter at 5.655 GHz, 200 kW peak, and the spherical model was irradiated using a pulse-type cavity oscillator at 1.10 GHz, 4 kW peak. Hydrophone transducers were implanted in the models to record the microwave-induced mechanical vibrations. Four properly timed radar pulses produced a threefold increase in the acoustical amplitudes in the muscle model. In the spherical model, a pulse train of three properly timed microwave pulses doubled the stress wave amplitudes as recorded by the implanted hydrophone. These results show that certain pulse parameters of microwave irradiation can be adjusted to increase the intensity of induced mechanical vibrations in both rectangular and spherical tissue equivalent models.