Transparent Monopole Antenna With EBG Array for Wearable Applications

This paper presents a compact, low-profile, transparent and flexible monopole antenna backed with a $3\times 3$ array of electromagnetic bandgap (EBG) structures. The reflection phase of a single EBG cell is investigated under various conductor layer sheet resistances. After meshing the conductor layers of the EBG structure, the variation of the zero-reflection phase frequency point as well as the bandwidth of the EBG cell is revealed. For planar monopole antennas, the optimized transparent EBG structure is employed to minimise backward radiation. The proposed antenna covers the 2.4 GHz industrial scientific medical (ISM) band. The antenna's high gain and low backward radiation in the operational band are confirmed by full-wave simulation. The EBG structure not only reduces backward radiation, but it also protects the human body by preventing the monopole antenna from radiating electromagnetic waves into body tissues, as well as minimizing frequency detuning induced by the human body. To ensure robustness and light transmittance, the proposed antenna was constructed on a transparent and flexible PDMS substrate. The proposed antenna's specific absorption rate (SAR) assessment showed that it is likely to be integrated into wearable devices for a variety of applications, especially in biomedical technology.