Design of Axial-mode Helical Antennas for Doppler-based continuous non-contact vital signs monitoring sensors

Abstract

An Axial-Mode Helical Antenna (AMHA) design for applications in Doppler-based continuous non-contact vital signs (NCVS) monitoring sensor systems is presented. Two methodologies of on-reflector impedance matching are presented as a solution to the helical antennas' non-50Ω input impedance issue. The antennas are evaluated on their performance of VSWR, impedance, radiation pattern directivity, size and gain. A size reduction design process is given for custom sizing the helical antenna, and the resulting structures are compared versus a patch antenna at 2.4GHz that is often used in NCVS systems. Our test data indicates that an AMHA can significantly increase accuracy of NCVS systems by increasing the system's Signal-to-Noise-and-Interference Ratio (SNIR).