Improved Throat Vibration Sensing with a Flexible 160-GHz Radar through Harmonic Generation

Speech can be recorded contact-free using the Doppler effect with a radar microphone and comprehensible results can be achieved even in a noisy environment. For that purpose, the transmit frequency must be higher than 100 GHz to measure enough harmonics of the skin vibration. This paper presents a 160 GHz radar MMIC with a transition to a flexible dielectric waveguide and a plugged antenna for a radar microphone application. With the flexible antenna front-end made of high density polyethylene a comfortable and easy attachment similar to an ordinary microphone is possible. The measured speech signals are comprehensible with the fundamental frequency and at least three harmonics. The background noise does not affect the speech signal as proven in measurements.