| With the development of science and technology,wireless electronic communication systems are increasingly used in biomedical fields,including cochlear implants,neural signal recording systems,wireless capsule endoscopy systems,and peripheral nerve micro-actuator.These medical devices have brought new options for diagnosis,monitoring and treatment of diseases.The wireless capsule endoscope system is a comprehensive system integrating information communication,photoelectric engineering,biomedicine and image processing,which is composed of numerous small components,including cameras,batteries,antennas and so on.The wireless communication antenna for data transmission is an important part of the system.Compared with the traditional antenna,its application environment has great complexity and limitations in the human environment.The traditional antenna can not meet the requirements of the WCE system because of the large size,narrow bandwidth and complicated structure.The antenna for the application of this system is developing in the direction of miniaturization,multi-function,wide frequency band and easy conformality.In order to meet the requirements of the antenna for wireless capsule endoscope system,this paper proposes a new type of dual-arm helical antenna structure,studying the characteristics of miniaturization and wide frequency band of the antenna.It mainly includes the following parts:Firstly,it introduces the development trend of wireless electronic application system in the field of biomedicine.Meanwhile,it introduces the research status of the antenna of the wireless capsule endoscope system at home and abroad,and makes a comprehensive analysis of the different types of antenna performance applied to the system.After clarifying the structure and performance of the antenna in the system,the main work is derived.Secondly,it introduces the working principle of the antenna and various basic parameters to measure the electrical performance of an antenna,including direction function,pattern,efficiency,gain,input impedance,polarization,bandwidth and effective area.The basic structure of the helical antenna and the working mode under different conditions are introduced.The polarization and radiation characteristics of the helical antenna in the normal mode radiation are analyzed with emphasis.Next,two capsule antennas were designed.A dual-arm helical antenna is composed of four layers circular spiral patches with a working frequency of 2.4 GHz,a patch diameter of 11 mm,athickness of only 1.1 mm,a bandwidth of about 2.5 GHz.Because of a high dielectric constant substrate Rogers RO3010,the antenna is miniaturized well.A flexible dual-arm helical antenna using polyimide as the substrate is mounted on the inner wall of the capsule with a diameter of11 mm and a height of 11.8mm.It is easy to conformal and makes full use of the system space with an ultra-wideband.The influence of the width and length of the spiral arm on the return loss and the resonant frequency of the antenna is analyzed.Finally,the two dual-arm spiral capsule antennas are both manufactured,and their electrical properties are analyzed through the physical test. |
PDF Full Text Request