Design Of Wearable Antenna Applied To Wireless Body Area Network

With the popularization of 5G mobile communication technology,wearable antennas used in wireless body area networks have broad application prospects in medical,Internet of Things,military and other fields.The design of a wearable antenna needs to consider the complex electromagnetic characteristics of the human body and the special application environment.In order to meet the application requirements,it not only needs to have structural characteristics such as small size,low profile,easy to conform to the human body.It should also have performance characteristics such as strong bending robustness,good human body loading performance,and meeting the health standards of the antenna's radiation to the human body.Strict requirements increase the difficulty of designing wearable antennas.At present,most wearable antenna designs are difficult to achieve both excellent structural characteristics and good performance characteristics.The design of a wearable antenna proposed in this paper takes into account these excellent features at the same time.First of all,for most planar wearables,the antenna has a high specific absorption rate(SAR)to the human body due to the omnidirectional radiation pattern.This paper proposes a dual-frequency wearable antenna based on an electromagnetic band gap structure,which achieves extremely low SAR value while also having high radiation efficiency,small size.Then,in order to realize a wearable antenna that takes into account both excellent structure and performance characteristics,a wearable antenna based on a flexible material and a very simple structure combined with a flat antenna and a"floating ground backplane"is proposed.The simple structure can maintain good robustness when the antenna is bent.The floating ground backplane can act as a reflector,introducing isolation between the antenna and the human body,achieving a low SAR value and obtaining good human body loading performance.Detailed performance analysis shows that the design of the antenna achieves the characteristics of low SAR value,strong bending robustness,good human body loading performance and high gain.It also has a flexible,easy-to-human conformal and small-sized structure.The characteristics make the proposed antenna a preferred candidate for most wearable applications for wireless body area network communication.The main research contents of this paper are as follows:1.A wearable monopole antenna based on an electromagnetic band gap structure is proposed,which works in ISM 2.45 and 5.8 GHz dual frequency bands for wireless body area network wearable applications.The SAR value of the monopole antenna radiated to the human body with and without the electromagnetic band gap structure is studied in detail.The research results show that the electromagnetic band gap structure effectively isolates the antenna's radiation to the human body.Compared with the antenna without the electromagnetic band gap structure,the electromagnetic band gap structure reduces the SAR value of the antenna to the human body by more than 97.5%,and also improves the antenna's SAR value.The gain is 9.1 d Bi at a frequency of 5.8 GHz.In addition,the antenna has the characteristics of small size and wide frequency band,which is suitable for wearable applications.2.A wearable flexible microstrip antenna based on a floating ground backplane is proposed,which works in the ISM 5.8 GHz frequency band.The microstrip antenna consists of a planar antenna and a floating ground backplane.The dielectric substrates of both are made on the flexible GD-401 silicone rubber with a volume of 50×25×0.5 mm³,a dielectric constant of 3.2 and low cost.,Use YC-01 epoxy resin conductive silver glue instead of traditional metal materials as the radiation patch/ground plane,so that the antenna has the characteristics of flexibility and stretchability,and is easy to fit with the human body.When the antenna is placed on a high-loss human body,it can maintain good impedance matching and has a peak gain of 5.6 d Bi.The S₁₁and radiation pattern performance of the antenna under 8 different bending radii and 8 different fold conditions are studied.Simulation and experimental results show that bending and wrinkles have little effect on the S₁₁and radiation pattern of the antenna.Research has shown that the antenna has strong bending and deformation robustness.In addition,the research also found that the proposed floating ground backplane structure significantly reduces the backward radiation of the planar antenna,which enables the antenna to obtain a very low SAR value.