| With the rapid development of wireless communication technology in the 21 st century,people's requirements for mobile communication equipment are getting higher and higher,miniaturized,multi-functional and low-latency intelligent communication devices are favored by the market.Antenna is an indispensable transceiver and transmission device in the field of information interaction,the quality of information interaction of wireless communication equipment is determined by the quality of antenna performance.The new generation of wireless communication technology(5G)has entered the stage of full commercial use,the range of communication frequency bands in the communication system is constantly changing.Low-performance narrowband antennas on wireless communication equipment will be eliminated,The ultra-wideband antenna with high performance has become the new favorite of today's researchers.The broadband antenna technology in small mobile communication devices such as mobile phones and tablets has become mature.However,the rise of driverless technology has brought new application prospects for ultra-wideband antennas.This thesis focuses on the research on ultra-wideband antennas used in the field of in-vehicle communication.The main contents of this thesis are as follows:(1)This thesis analyzes the application scenarios of today's ultra-wideband antennas,the comparison shows that the field of vehicular communication has become a new research direction of ultra-wideband communication antennas.Then,the types of ultra-wideband antenna miniaturized antennas are studied,and the methods of extending the bandwidth and miniaturization methods of domestic and foreign scholars are summarized,compared and analyzed.(2)This thesis mainly introduces the antenna performance indicators and MIMO antenna technology of ultra-wideband antennas used in the field of in-vehicle communication.In this thesis,the antenna impedance matching method is systematically described to extend the impedance bandwidth,and the directionality,gain and radiation efficiency of the antenna are theoretically analyzed.In addition,this thesis also introduces the method of improving isolation in MIMO antennas,and introduces the concept of envelope correlation coefficient to explain the electromagnetic coupling between MIMO antennas.(3)In this thesis,the microstrip antenna is combined with the monopole,and the design process and radiation principle of the printed microstrip monopole antenna are analyzed.The antenna is mainly composed of "hui" type microstrip radiation branches and ground coupling branches,which are mounted on the FR-4 dielectric substrate and placed vertically on the shark fin metal floor to form a vehicle-mounted MIMO antenna.This thesis uses antenna bending technology to achieve miniaturization,uses ground coupling stubs to extend impedance bandwidth.The antenna is simulated by software and processed and measured,and finally realize the ultra-wideband working frequency band of 0.82?0.96 GHz and1.71?6GHz,covering GSM850,GSM900,DCS1800/PCS1900,UMTS2100,LTE2300,LTE2600,5G and V2 X,The maximum gain of a single antenna can reach 8.1d Bi.the final size of a single antenna is 50mm×40.6mm×1.6mm.(4)In this thesis,a planar monopole ultra-wideband antenna with high isolation and high stability is designed for the vehicle MIMO antenna.The antenna consists of 1/4elliptical monopole stubs and rectangular monopole stubs.The MIMO antenna is vertically placed on the shark fin metal plate to ensure the vertical polarization characteristics of the antenna,and the fabrication and processing of the antenna are facilitated.The metal floor is cut by space diversity technology so that the MIMO antennas are not grounded to reduce the surface wave coupling and improve the antenna isolation.The impedance bandwidth of the processed antenna can cover the ultra-wide working frequency band of 0.71?6GHz,and can cover multiple communication service frequency bands such as GSM,DCS/PCS,UMTS,LTE,5G and V2 X,The maximum gain of a single antenna can reach 8.1d Bi.The final size of a single antenna is 55mm×42mm×1.6mm.In this thesis,two solutions are proposed for the ultra-wideband communication antenna suitable for the field of vehicular communication.The feasibility of the solution is verified through theoretical research,radiation principle calculation,software simulation analysis,and actual measurement.A novel design idea and research method are provided for the vehicle-mounted antenna. |
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