Design of a Broadband Circularly Polarized Wearable Antenna Based on Flexible Materials

In this work, a broadband circularly polarized antenna for off-body communications is proposed. The structure consists of a driven element with C-shaped slot, as well as four corner-truncated patches surrounded with a non-uniform metasurface. The latter promotes bandwidth-enhanced operation by suppressing the highorder modes through reduction of coupling currents between the patches. To ensure mechanical flexibility, the antenna is implemented on a felt-based substrate, with metallization in the form of a copper adhesive tape. The radiator is characterized by a relative dimension of 1.06λ<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> × 1.06λ<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> × 0.096λ<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf>(at 5.8 GHz). Its operational bandwidth expressed in terms of impedance and 3dB axial ratio is 69.8% (4.24-8.79 GHz) and 34 % (5.46-7.70 GHz), respectively. Demonstrated robustness of the proposed radiator to structural deformations makes it suitable for wearable applications.