Research On Embedded Antennas In Flexible Wearable Media Based On 3D Printing Technology

The rapid development of the Internet of Things has brought spring to the terminal and stimulated the development of human-centered communication systems.The terminal needs have become diversified,the application scenarios have been diversified,and the electromagnetic environment has been diversified.Traditional antennas have been unable to meet the requirements of human-wearing communication systems.The flexible wearable antenna can cope with the complex application environment that changes with changes in human activities,so that the antenna can maintain good duplex communication ability even in a bent state,and can also ensure stable electromagnetic performance while conforming to the human body.The combination of the dielectric embedded antenna and the flexible wearable antenna can improve the performance of the flexible wearable antenna in concealment,corrosion resistance and mechanical resistance in practical applications.It breaks the limitation of the application of the traditional antenna on the surface of the human body,and solves the application problem of the antenna in the flexible wearable communication system of the human body.This paper focuses on dielectric embedded antennas combining FDM 3D printing technology and flexible wearable antennas,and designs antennas based on the characteristics of flexible wearable antennas and dielectric embedded microstrip antennas.Because FDM 3D printing technology has many advantages such as high degree of automation,high precision,high degree of manufacturing freedom,material saving,environmental protection,etc.,it can bring greater value to the research of flexible dielectric embedded antenna.Firstly,Ninja Flex,the excellent 3D printed filament,was selected as the flexible dielectric material and dielectric embedded material of the antenna.In order to avoid different material properties caused by different 3D printing processes,the permittivity and loss tangent of the model were determined during the printing process and tested for the antenna design.Provide reliable material data support for antenna design.Based on the basic theory of the dielectric embedded microstrip antenna,a small size 60 mm × 60 mm Ninja Flex flexible wearable dielectric embedded antenna based on 3D printing technology is designed with conductive fabrics,which works in the ISM band and Wi MAX band.The dielectric embedded layer provides mechanical and chemical protection to the flexible wearable antenna.The input impedance of the antenna is 50?,which is easy to integrate with the RF circuit and adopts the microstrip line feeding method to improve the comfort of the flexible wearable antenna.The effects of Ninja Flex overlay on antenna performance,the effect of infill percentage on antenna return loss and axial ratio,surface current changes,and safety were analyzed.The electromagnetic performance and waterproof performance of the antenna when tested with flat,25 mm radius,and 50 mm radius were tested.The simulation and test results are in good agreement.The antenna has a stable operating bandwidth of 11% and a circular polarization bandwidth of 70 MHz.It radiates right-handed circularly polarized waves and has a circularly polarized radiation range up to 160 °.Suppressing rain and fog interference and resisting multipath effects.The maximum SAR value is 0.6W/kg,the maximum efficiency is 30.7%.It has good security,washability and concealment.As the conductive fabric has good flexibility and ductility and Ninja Flex has good elasticity,the antenna can return to flat state by itself after being bent,and has good self-healing performance in terms of mechanics.