Research And Implementation Of Flexible Antenna For Wearable Wireless Communication System

With the development of wireless communication technology and the rising popularity of intelligent terminals,body area networks as a new form of networks has been one of the hotspots in the present academic circles.Meanwhile,wearable electronics with the characteristics of intelligent,beautiful,portable and wearing comfort,etc.are generally favored by the majority of consumers.Body area network is an important part of the fourth generation of mobile communication,and flexible wearable antenna is a focus in the study of human center network antenna.The research of flexible wearable antenna with low profile,easy to carry and conformal with body and other characteristics has important implications.This paper mainly concerns with the design and research of flexible wearable antenna for wearable wireless communication system.The main contributions are as follows:(1)Mastering basic theories and knowledge of antenna design.The preparation methods and technological process of flexible wearable antenna was studied,and the achievements and trends of flexible wearable antenna were learned.Reasearch on the different ways to realize the flexible wearable antenna based on different dielectric substrate and conductive patches,and the influence of the electrical conductivity of radiation patch on the performance of the flexible antenna.Meanwhile,the conductive mechanism and the method to improve the electrical conductivity of conductive patches were characterized.(2)The operating principle,structural parameters and fabrication process of the proposed antenna were illustrated,and the method to enhance the electrical conductivity of silve adhesive and the electrical characteristics after film-forming were researched.The proposed antenna can achieve reflection coefficient(S11)of-26 dB and-28 dB at the center frequency2.45 GHz and 5.8 GHz,respectively.The measured VSWR(Voltage Standing Wave Ratio)is1.5 and 1.8,respectively.The radiating properties were also characterized and the measured results show a good correlation with the simulated results.Bending model was set up to explore bending effect the performance of the dual-frequency flexible wearable antenna.The simulation and measurement results were presented to demonstrate the effective of the approach.(3)Resaerch on the application of injet printing in flexible wearable antenna,a fully printed CPW-fed antenna worked at 3.6 GHz WiMAX band was propsed in this paper by the way of spray print silver nanoparticles on PET flexible substrate.The geometry,dimensions,fabrication process and characterization methods for performance of the proposed antenna were illustrated,and the technology methods to improve and optimize the electrical conductivity and mechanical properties of the radiation patch prepared by injek printing nanoparticles.The influences on the performance of the fully printed CPW-fed flexible wearable antenna with different bending radius were introduced.The simulated and measured reflection coefficients are ~-36.7 dB and ~-23.8 dB,respectively.Meanwhile,the-10 dB bandwidth is ~180 MHz and the obtained VSWR is ~1.3.Radiating properties were characterized and agree well with the simulation results.The material and fabrication technique illustrated here could be extended to achieve other types of flexible antenna with more complex patterns for wearable electronics applications.(4)A flexible wearable textile microstrip antenna worked at 2.45 GHz ISM band was proposed in this paper.Textile was used as the flexible substrate and polydimethylsiloxane(PDMS)filled with graphene nanoplatelets(GNPs)and polyaniline(PANI)was prepared for highly conductive radiating patch and ground plane.The design principle and preparation methods of flexible textile wearable antenna were researched,and the structual features and fabrication process of the proposed microstrip antenna were illustrated.Meanwhile,the conductive mechanism and performance characteristics of the GNPs/PANI/PDMS composite materials were studied.The simulated and measured reflection coefficients are ~-36.2 dB and ~-22.6 dB,respectively.Meanwhile,the-10 dB bandwidth is ~165 MHz and the obtained VSWR is ~1.58.The radiating properties were also characterized and the measured results showed a good correlation with the simulated results.Bending model and three-layer tissue model was built in HFSS(High Frequency Structure Simulator),and the effect to the performace of the antenna under bent was studied.The SAR(Specific Absorption Rate)values with different distances were given to evaluate the effect of the textile microstrip antenna on hunman body.The results show that the ground plane of the proposed textile microstrip antenna can effectively reduce the radiation to human,and the SAR meets the required standards.According to the basic design theory of antenna and the development needs of the flexible wearable antenna,the methods and implementation of flexible antenna were introduced,which provide a feasible solution to the design and development of flexible antenna for wearable wireless communication system.