In our research, a custom picosecond pulse radiator is used to demonstrate the micro-Doppler phenomenon in the Terahertz (THz) regime. In the micro-Doppler effect, the periodic movement of radar targets modulates the frequency of the electromagnetic waves reflected from their surface. The modulation depth is dependent on the intensity of the vibrations and the carrier frequency. Therefore, using carrier tones in the THz regime enables detection of weak micro-Doppler signatures. In this experiment, sound vibrations with frequency of 50 to 700 Hz were used to modulate a 395.2 GHz carrier signal produced by a digital-to-impulse (D2I) silicon chip.
Results included a ten-second music track, a chirp sound, and multiple frequency tones were produced by a speaker and then were reconstructed through the micro-Doppler effect. The sound waves were recovered via frequency demodulation at the receiver.