Design and Evaluation of Typical Antennas for Monitoring Vital Signs

Non-contact method to monitor vital signs using radar-based sensor system is a more convenient way in comparison with the contact monitoring devices. Portable with a low profile and low-cost non-contact vital signs sensors system that are capable to monitor heart and respiration rates are presented and evaluated their performances. A printed 2x1 patch array antenna, Yagi-Uda antenna and dipole array antenna are designed and integrated with sensor system Tx/Rx module for their performances analysis. The gain of the designed antennas are 6.38 dBi, 7.7 dBi, and 10.5 dBi, VSWR are 1.1, 1.15, and 1.0, and return loss are -26.26 dB, -22.7 dB and -21.6 dB respectively at 2.4 GHz. The evaluations performances of these antennas were compared with a standard respiratory-rate measurement using a pulse sensor and respiratory sensor. The measurement results using the proposed non-contact sensor systems and the standard contact systems showed excellent performance with the printed dipole array antenna compared with other two antennas, the error between the average heart rate extracted by the non-contact systems and the reference systems are ±1.1 beat/min for dipole array antenna, ±1.5 beat/min for printed 2x1 patch array antenna and ±1.9 beat/min for Yagi-Uda antenna.