Non-contact measurement of periodic movements by a 22-40GHz radar sensor using nonlinear phase modulation

A non-contact detection technique of measuring both the frequency and the amplitude of periodic movement using the property of nonlinear phase modulation is proposed and demonstrated by a 22-40GHz radar sensor. It is shown that this method has the following advantages: 1) no calibration of signal amplitude required for accurate measurement of movement amplitude; 2) ability of self-verification; 3) very simple architecture. The method can be used to detect movements with amplitudes larger than 0.335 of the carrier wavelength for a fixed carrier frequency system and 0.214 of the minimum carrier wavelength for a frequency tunable system. By analyzing and simulating the wide angle incidence effect, it is shown that a proper choice of radio frequency, measurement distance, and antenna pattern can ensure accurate measurement of movement amplitudes.