24 GHz Flexible LCP Antenna Array for Radar-based Noncontact Vital Sign Monitoring

Noncontact monitoring of human vital signs is an emerging research topic in recent years. A key approach to this monitoring is the use of the Doppler radar concept which enables real-time vital signs detection, resulting in a new class of radar system known as bio-radar. The antennas are a key component of any bio-radar module and their designs should meet the common requirements of bio-radar applications such as high directivity, circularly polarized and flexibility. This paper presents the design of a four-element antenna array on a flexible liquid crystal polymer (LCP) substrate of 100 μm thickness and ε
_r
of 3.35. The designed antenna array can be used with a 24 GHz bio-radar for vital signs monitoring in a non-contact manner. It features a compact size of 27.56 × 53 mm and relatively high gain of 6.17 dBi.