Flexible EBG Structure For Broadband And High Gain Antenna Design

With the rapid development of modern communication technology and the popularization of wearable devices,the importance of antenna design in communication systems has become increasingly prominent.Traditional antennas made of metal materials are limited in terms of flexibility and pliability.Wearable antennas made of conductive textiles exhibit excellent flexibility and pliability,making the study of wearable antennas based on conductive textiles highly significant.To meet the demands of wearable devices in terms of communication performance,user experience,and various application scenarios,wearable antennas should aim to achieve wide bandwidth and high gain.The integration of Electromagnetic Band Gap(EBG)structures can effectively regulate and optimize antenna performance without altering its size and shape.Therefore,this paper focuses on the design of EBG structures,with specific content as follows:Firstly,the impact of EBG structures on their bandgap characteristics was analyzed,and single-layer EBG structure designs based on polygons,mushroom structures,shape combinations,array layouts,and other methods were conducted.The results show that these single-layer EBG structure designs can achieve multiple narrowbands but cannot realize a single wideband characteristic within a large frequency range.On this basis,a novel dual-layer EBG structure is proposed.By utilizing the different transmission and reflection effects of each layer in the dual-layer structure,this structure exhibits significant advantages in terms of bandwidth enhancement,gain improvement,bending resistance,and insensitivity to antenna types.When the dual-layer EBG structure is placed on the antenna,simulation results show that the antenna bandwidth increases from 6.98% to 10.47%,and the antenna directional gain is improved from 7.33 d Bi to 10.4 d Bi.Through measurements,the enhancement effect on antenna gain is verified,with a measured forward radiation gain increase of 3.54 d B.Furthermore,the optimization effect of the proposed dual-layer EBG structure on antenna radiation performance is not limited by the type of single linearly polarized antenna.It can still maintain the relative stability of antenna gain when the antenna metal ground plane is reduced to 72% of its original area.Therefore,this dual-layer EBG structure provides a promising solution for wearable antenna design.