Research On Flexible Wearable Fractal Antenna

Wearable antenna is a new technology,which can be used in many fields,including military,telemedicine,sports and tracking.Wearable antenna requires the antenna to work normally near the human body,while working normally under bending conditions.With the development of wireless communication,the performance of wearable antenna is demanded more and more.Ensuring the comfort,miniaturization,multi-frequency and even ultra-wideband(UWB)of wearable antenna is the development direction of wearable antenna.Fractal geometry has the characteristics of infinite complexity,fractal dimension,self-similarity and space filling.These fractal characteristics can be applied to the design of antenna,which can make the antenna have the characteristics of miniaturization,multi-band and anti-damage.In this paper,the flexible wearable fractal antenna is studied.Combining the advantages of fractal antenna,a variety of wearable flexible fractal antennas with miniaturization,multi-band and even ultra-wide band are designed.The structure of these antennas is simulated and optimized on the full-wave electromagnetic simulation software HFSS,and some of them are manufactured.The main research contents are as follows:1.The multi frequency technology of fractal wearable antenna is studied.The principle and significance of multi frequency technology of fractal antenna are analyzed.Two kinds of antenna multi-frequency technology are introduced,including inverse F multi-frequency antenna based on Hilbert fractal and pentagonal fractal multifrequency antenna with electromagnetic band gap(EBG).Both antennas are based on fractal theory to improve the antenna structure,and the performance of the antenna is verified by software simulation.As a result,the antenna achieves multifrequency function by fractal.2.The miniaturization technology of fractal antenna is studied.The structure of the miniaturized UWB hexagon antenna based on Koch fractal,the Koch fractal miniaturized hexagon antenna based on polyimide and the wearable miniaturized UWB antenna based on polyimide are analyzed.The simulation and optimization are carried out on HFSS software.The results show that the size of the antenna decreases with the addition of Koch fractal structure.On the basis of making a physical object,the simulation is verified,and the manufacturing process of miniaturized antenna and matters needing attention are explored.3.The wearable characteristics of antennas are studied.It is divided into three parts: the influence of human body on antenna performance,the influence of human activity on antenna performance and methods to reduce the influence of human body on antenna performance.In the study of the effect of human body on antenna performance,the following three aspects are studied: the high dielectric constant of human body,the HFSS simulation of antenna on human body surface and the performance of antenna on human body surface;In addition,the effect of human activity on antenna performance is discussed by HFSS simulation of antenna bending and the effect of antenna bending on antenna performance,and the effect of adding EBG structure on reducing antenna performance change is discussed.