Optimal Carrier Frequency of Non-contact Vital Sign Detectors

Simulations were performed based on a model developed in ADS to demonstrate the effects of non-linear cosine transfer function in non-contact vital sign detection. Harmonics and intermodulation effects have been analyzed theoretically and demonstrated by simulation. It is shown that in contrast to the observation from simple linear approximation that detection sensitivity always increases with carrier frequency, there is an optimum carrier frequency for non-contact Doppler radar vital sign detection. For typical values of human chest wall movement, the simulation shows that the upper bound of the carrier frequency should be limited to the lower region of the Ka-band to improve detection accuracy