Study Of The Metasurfaces Applied In Wearable Antennas

As an important communication device in wireless body area network,wearable antennas must meet specific requirements,such as compactness,lightness,flexibility,easy integration,security,etc.In order to maintain reliable communication and ensure the comfort and safety of the wearer.Metasurface shows excellent performance in expanding bandwidth,increasing gain and reducing size of antennas.The metasurface is applied to the design of wearable antennas,and three metasurface wearable antennas are designed in this paper.The working band of the designed antenna can be applied to2.4 GHz(2.4-2.4835 GHz)and 5 GHz(5.15-5.825 GHz)WBAN bands,The contents of the study are as follows:A miniaturized high gain metasurface wearable antenna is proposed in this paper.The method of extracting equivalent electromagnetic parameters is used to make the metasurface equivalent to a dielectric layer with high dielectric constant,which realizes the miniaturization of the antenna and improves the gain.The return loss of the antenna without metasurface and loaded with equivalent dielectric layer is compared to prove the rationality of the size reduction and equivalent electromagnetic parameters.The antenna has a peak gain of 6.67 d Bi and a bandwidth of 2.34-2.58 GHz,which can cover the 2.4 GHz WBAN band.A broadband non-uniform metasurface wearable antenna is proposed in this paper.Based on the transmission line theory,the TM₀₁ and TM₀₃ modes of the metasurface are analyzed.By adjusting the structural parameters of different units of the metasurface,the resonant frequencies of the two modes are adjusted to achieve bandwidth expansion.Compared with the traditional method of adding pin or slotting to adjust the resonant frequency of the mode,the method proposed in this paper is easier to operate.The-10d B impedance bandwidth of the antenna is 1.47 GHz(4.72-6.19 GHz),and the functional bandwidth is 26.9%.The antenna can cover the 5GHz WBAN band with a peak gain of 8.54 d Bi.A dual-band dual-mode metasurface wearable antenna is explored in this paper.The omni-directional mode of circular metasurface is introduced to expand the bandwidth of the antenna.The characteristic mode theory is used to analyze the radiation mode of the metasurface,and the equivalent circuit model is used to calculate the resonance frequency of the metasurface mode qualitatively.The antenna can cover2.4 GHz and 5 GHz WBAN bands at the same time.Compared with other dual-band dual-mode antennas in the same band,the antenna has obvious advantages in bandwidth.In this paper,the metasurface structure is applied to the design of wearable antennas,which improves the antenna performance in the aspects of structure miniaturization,bandwidth expansion and gain enhancement,and enriches the study and design methods of wearable antennas.