Microwave Wide-Area Self-Injection-Locked Radar for Wrist Pulse Detection

Radar-based near-field wrist pulse detection systems currently face robustness challenges, particularly when dealing with different subjects and alignment discrepancies. These limitations restrict the applicability of such systems in practical settings. Addressing these challenges, this article introduces a wide-area self-injection-locked (WASIL) radar system to enhance near-field wrist pulse detection performance. The proposed system integrates a complementary split-ring resonator (CSRR) antenna array with a substrate-integrated waveguide (SIW) filter, which broadens the detection range and improves the system’s robustness against different subjects and alignment discrepancies, which are commonly faced in traditional self-injection-locked (SIL) radar applications. In addition, a simulation model of the CSRR antenna, which incorporates customized dielectric constant parameters of the skin, has been established to simulate the dynamic effects of wrist pulse on antenna performance. Experimental results confirm that the WASIL system markedly improves pulse detection capabilities across extensive areas. The detection range has been increased by 255.6% in comparison to the most effective SIL system currently available, which utilizes a single CSRR. This expansion in detection range and demodulation capability improves the system’s robustness, allowing for reliable operation in wrist pulse detection.