Research On Ultra-Wideband Miniaturized Antenna Technology And Its Application

With the advent of the 21st century electronic information age and the continuous development of positioning technology,people not only need outdoor location service,but also have the same urgent demand for indoor accurate location.Due to its unique advantages,ultra-wideband(UWB)positioning system has become the most widely used indoor positioning technology.The time-domain UWB antenna,which used to transmit positioning information,is one of the most important parts of the positioning system.Its performance directly affects the positioning accuracy and distance of the UWB system.In this paper,the time-domain UWB antenna applied to UWB indoor precise positioning system is studied in the following aspects:1.In this paper,the commonly used indoor positioning system is compared,and the advantages of UWB indoor positioning system are obtained.This paper studies the development history of time-domain ultra wideband antenna,and summarizes and compares the miniaturization technology and bandwidth expansion methods of time-domain ultra wideband antenna commonly used by scholars at present.2.This paper introduces the basic parameters and measurement indexes of the time-domain ultra wideband antenna for ultra wideband positioning system,introduces the basic theory and basic index parameters of the flexible antenna,analyzes the radiation safety of the flexible antenna(the introduction of SAR)and theoretically analyzes the electrical characteristic model of human skin tissue.In addition,the additional performance index and characteristic requirements for UWB positioning antenna are introduced.3.The evolution process and radiation principle of monopole antenna are analyzed,and the broadband process of monopole antenna is discussed.The effect of extending current path on bandwidth expansion was studied by grooving and bending the floor and radiation patches.Based on the theory of artificial electromagnetic metasurface,the effect of artificial magnetic conductor(AMC)surface on antenna miniaturization,reduction of profile and increase of gain is studied.The AMC surface is combined with a monopole antenna to design a wearable antenna with high gain and unidirectional radiation characteristics.The electrical characteristic model of human skin tissue is designed to simulate the absorption of antenna radiation by human body,and the radiation effect of wearable antenna on human body is studied.4.Starting from the study of cavity mode theory,the equivalent model of resonant cavity of patch antenna is discussed,and the way to expand the bandwidth of circular patch antenna is explored.The bandwidth is expanded by increasing the thickness of the dielectric substrate to reduce the quality factor Q,adding a capacitive ring slot to compensate the reactance of the probe,and adding a short-circuit through hole to adjust the resonant frequency.The combination of TM₀₁,TM₀₂ and TM₀₃ three resonant modes is successfully realized,and an ultra wideband patch antenna with short-circuit parasitic ring and stable monopole radiation characteristics is designed.5.The structure and construction of UWB indoor precise positioning system are studied,and the principle,advantages and disadvantages of TDOA algorithm commonly used in positioning are analyzed.Based on the TDOA algorithm,the UWB indoor precise positioning system is built,the time-domain performance of the designed UWB antenna is verified,and the actual positioning effect of the two designed antennas in indoor positioning is explored.