A Lightweight Flexible Wearable Circularly Polarized Antenna for Navigation and Positioning in IoT Applications

In this article, a lightweight, flexible, wearable circularly polarized antenna for navigation and positioning in Internet of Things (IoT) applications is proposed. The proposed antenna is etched on a polyimide (PI) substrate with dimensions of 77.9 mm $\times 73$ .2 mm $\times 0$ .2 mm. The antenna consists of a feed branch, coupling branch, and peripheral annular ground, and it is fed using a coplanar waveguide (CPW) method. The fabricated antenna prototype demonstrates an operational bandwidth of 1100–2300 MHz, an axial ratio (AR) bandwidth of 1100–1700 MHz, and a half-power beamwidth (HPBW) of 101°. Measurement results align well with simulations, showing stable performance under various bending conditions and when worn at different body locations. Additionally, in outdoor satellite tracking tests, the proposed antenna was worn at various body positions, tracking up to 51 satellites with a positioning dilution of precision (PDOP) of 0.876. Compared with three commercial GNSS antennas, the proposed antenna offers a low profile and robust satellite-tracking performance, highlighting its potential as a navigation and positioning tool in IoT applications.