Non-contact Vital Signs And Radar Detection System Antenna Design

Doppler radar has been widely used in a number of applications, including vehicle speed measurement and storm tracking. The same principle, the non-contact remote detection of vital signs lead to several potential application, such as searching for survivors after earthquake and monitoring sleeping infants or adults.CW radar with the human body as the target will receive a signal with its phase modulated by the time-varying chest-wall position. Demodulating the phase will then give a signal proportional to the chest-wall position that contains information about movement due to heartbeat and respiration. Therefore, detecting the frequency or phase shift in a reflected radar signal, can be used to detect tiny physiological movements. Non-contact solution neither confines nor inhibits the subject, it is especially important over extended periods of time, making the detector ideal for long-term continuous monitoring applications.This dissertation begins with the spectral analysis of the quadrature demodulator structure. The harmonic and intermodulation issues caused by the non-liner Doppler phase modulation will be discussed in detail. Analyses will illustrate the method for optimal design of carrier Frequency. Then this thesis analyzes the distributing of the null points and optimum points of the frequency-tuning double sideband structure, while spectral analysis was carried out. Because this technology is now moving in the direction of smaller form factor, longer detection range, the design of high-gain and easy integration of miniaturized antenna arrays will be especially important. By etching longitudinal slots on the top metallic surface of SIW, integrated slot array antennas are formed. Therefore, the electrical characteristics of the SIW slot were thoroughly analyzed, and Elliott’s three design equations were employed to design SIW slot arrays which could be integrated in the vital signal detection system.