Compact Circularly Polarized Wearable Button Antenna With Broadside Pattern for U-NII Worldwide Band Applications

A novel circularly polarized button antenna is proposed. The antenna is constructed on a disk-shaped FR-4 substrate. This disk is located on the top of a textile layer and supported by a feeding probe. The antenna works in the 5.47-5.725 GHz Unlicensed National Information Infrastructure worldwide band, with over 14% relative impedance bandwidth and over 7% relative axial ratio bandwidth. A prototype has been fabricated and measured. A good agreement is found between measured and simulated results.