Monitoring of Human Cerebral Hemodynamic Signals Through a Microwave System

This study presents a novel microwave system designed for monitoring of human cerebral hemodynamics. The system comprises a wearable belt with two antennas connected to a 2-port Vector Network Analyzer (VNA) via coaxial cables. Utilizing an ultra-wide bandwidth antenna (relative bandwidth $=103 \%$, dimensions: $17 \mathrm{~mm} \times 17 \mathrm{~mm} \times$ $2.54 \mathrm{~mm},\lt 0.31 \lambda$), the system operates in the frequency range of 800 MHz to 2.7 GHz, specifically tailored for working with human head. Simulation and measurement results on a volunteer’s head align, confirming the antenna’s efficacy. Cerebral hemodynamic signals were recorded through a laptop-controlled network analyser at a rate of 15 times per second. Analysis of the recorded S-parameters illustrates the system’s capability to record 1D cerebral hemodynamics signal corresponding to the volunteer’s heart rate.