Monitoring vital signs using remote harmonic radar concept

The purpose of this work is to demonstrate the feasibility of non-contact or remote vital signs sensing or monitoring using a new concept called "harmonic radar". The proposed demonstrator is based on the use of system components (VCO, coupler, antenna, LNA, mixer) operating at both the fundamental frequency (12 GHz in this work) and its second harmonic frequency (24 GHz). The designed radar transmits and detects both fundamental and second harmonic waves that are used to create frequency diversity for parametric detection and estimation. Numerical and experimental results are presented to validate the proposed concept. It is shown that the accurate detection of vital signs can be obtained with such a remote harmonic radar technique. Furthermore, results obtained by using wideband antenna are compared with those obtained with two Substrate Integrated Waveguide antennas operating at two different frequencies, namely 12 GHz and 24 GHz.