Design and Optimization of a High Gain Thin-Film Flexible Antenna for 28 GHz Wireless Wearables

This paper proposes an antenna consisting of polyimide and fluoride synthesized multilayer thinfilm materials on a flexible substrate. The antenna is suitable for millimeter-wave applications at 28 GHz and can be applied to wearable devices by utilizing the flexible characteristics of the thin film. The application bandwidth is 26-30.5 GHz with a fractional bandwidth of 15.95%. At 28.9 GHz, it exhibits a maximum gain value of 11 dBi. This paper also analyzes the effect of antenna bending characteristics on antenna performance. It is verified that antenna bending does not affect the application frequency band and bandwidth, and it can generate beam shift. The antenna is made of a soft and extremely thin material, and through the antenna design and parameter optimization in this paper, the antenna has the ability to be comfortable to wear and maintain the performance of the antenna in daily applications. The antenna is very suitable to be combined with close-fitting clothing and does not affect human health as verified by the power density.