| With the introduction of "Digital Terrestrial Television Broadcasting Coverage Network Development Plan" in 2012,the promotion and application of terrestrial digital TV was raised to the height of strategy.As an important part of ground wireless transmission equipment,digital TV transmitting antenna directly affects the quality of TV broadcasting.The broadband,high gain digital TV transmitter antenna occupies less space,covers a wide range,and can meet multi-channel broadcast at the same time,thereby effectively reducing operating costs.Therefore,it is very important to study the antenna.This paper is done under the project of researching the broadband,high gain digital television transmitting antenna,which is launched by Liaoning Putian Digital Limited Company and processed in the Institute of Microwave and Antenna of Dalian Maritime University and the main work is as follows:(1)A UHF dipole four element plate antenna is designed and implemented.The antenna consists of two cylindrical dipole antenna in parallel as a group,composed of two element array.The two group of two element array by T power splitter is used for feeding,consisting of four dipole plate antenna.When designing a element antenna,the frequency band of the element antenna is broadened by introducing a compensating balun structure.The multi section complex impedance converter is added into the T power division feed network to realize the broadband matching of the four element plate antenna.The antenna simulation has 36%(543?783MHz)relative bandwidth(VSWR<1.15),the operating band gain is greater than 12.5dBi.The measured relative bandwidth is 58.6%(470?860MHz),the measured results of the antenna agree well with the simulation results.(2)In practical engineering,multi surface combination technology is usually used to realize the control of horizontal field type.In this paper,three kinds of engineering measures to achieve horizontal omnidirectional are analyzed theoretically and simulated.By summing up the roundness data of different TV Tower width,different placement mode and feeding mode,the reasonable layout method of the antenna in practical engineering is given.(3)The electrical beam tilt and mechanical beam tilt in vertical plane is analyzed,and the theoretical calculation results are verified by software simulation.Comparison of the vertical radiation pattern of two beam tilt mode,The reasonable way to achieve the declinational wave beam for the antenna designed in this paper is given. |
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