Design and implementation of a RF sensor with single-channel and nonorthogonal IQ signals for non-contacting monitoring

Abstract

In this article, a design of RF (radio frequency) sensor which is based on PCB (Printed Circuit Board) antenna for monitoring physiological parameters is proposed. In order to remotely monitor the activities of heartbeat, respiration and body movement, this article designed and implemented a RF sensor with single-channel and nonorthogonal IQ signals whose working central frequency is 2.4 GHz. Considering of low cost, simple structure and the ease of fabrication, the antenna is designed to be integrated into a circuit on a PCB to form a single antenna system. The gain of the sensor is 7.7 dB. The return loss is -22.7dB at 2.4GHz and the directionality of the antenna is satisfactory for monitoring vital signals. After simulation and some experiments, it was validated that the sensor could detect the respiration and movements signals.