Large-Scale Near-Ground Yagi Antenna Array

As one of the classics in antenna area,Yagi antenna includes advantages such as simple in structure,good end-fired,high gain,easy to process,etc.,and has been widely applied in both in civil and military uses.In engineering applications,a single antenna may not be suitable for specific operation environments or tasks,then multi antennas are required to form an array,to achieve extra characteristics such as narrow beamed,low sidelobe,multi-beamed,in order to improve practical performance.The large-scale Pband near-ground Yagi antenna array designed in this paper is formed with 316 Yagi antennas,which utilizes in a monopulse radar system.The array provides both sum beam and two lobes of the difference beam,which can achieve the distance tracking and angular tracking of flight targets by analyzing the echo signal.Because of the large size of the antenna array and work near the earth,it is necessary to consider the influence of infinite and large cost.In this paper,the discrete complex image method is used to solve the radiation characteristics of the array antenna under the influence of the ground.And finally draw the pattern and blakechart.The main content includes the following aspects:First,design a Yagi antenna array according to the requirements.And use the method of moments analysis of it,the Pocklington integral equation is applied to the solution of the current of the Yagi antenna,and solve the radiation characteristics of the Yagi antenna.Design a Yagi antenna flat array,using the Taylor distribution synthesis method,and solve the feed current distribution of the array element to determine the appropriate element spacing.The plane array is calculated by the method of moments,and the radiation characteristics are analyzed.Draw the sum-and difference-pattern,pitching pattern.Second,when the Yagi antenna plane array from the ground height is not high,consider the infinite large consumption of the face of a Yagi antenna plane array of radiation characteristics of the impact.It is known that the electric field of the electric dipole in the infinite half space contains the Sommerfeld integrals,and how to solve the Sommerfeld integral quickly and accurately is always a problem.Which is solved by discrete complex image method and function approximation method,and then applied to the solution of the radiation characteristics of large-scale near-ground Yagi antenna array.Draw the sum-and difference-pattern,pitching pattern.Thirdly,due to the influence of the ground,the main lobe of the elevation surface pattern will produce a serious split,considering the elevation angle of the array to solve this problem.The influence of elevation angle on the antenna array pattern is analyzed,and the radiation pattern of the plane array of Yagi antenna under different elevation angles is drawn and the blakechart is drawn.Finally,the physical test is carried out,and the results of the actual test are compared with the results of the analysis of the moments to determine the correctness of the research method.The final results show that the design of the Yagi antenna array meets the practical requirements.