Characterization of the Influence of Clothing and Other Materials on Human Vital Sign Sensing using mmWave Radar

In this work the effects of clothing and other fabric materials such as blankets on radar vital sign measurements are analyzed. The signal loss for six different materials at 61 GHz, 122 GHz and 175 GHz was measured using a modulated reflector on a test bench. In addition the effect of sweat in the fabrics at different concentrations was researched. It is shown, that thin fabrics show very little loss when they are dry but cause significant damping once they get wet. These results conclude, that the dampening effect of fabrics is not negligible for high frequency radar systems.