Design Of Large Short-wave Array Antenna For Sky-wave Over-the-horizon Communication

Sky-wave over-the-horizon communication is a very important communication method working in the short wave band.It plays a unique role in both military and civilian use.The quality of the transmitting and receiving antennas has a great impact on the quality of the whole communication system.Short-wave communication systems require antennas to achieve wide-band characteristics and high gain over the whole frequency band.At the same time,the antenna also needs to meet the beam pointing on the elevation plane.requirement of the elevation and azimuth plane.The short-wave antenna which requires supporting structures and ground network construction has a large physical size.Its manufacturing cost is very high.Designing a short-wave antenna with excellent electrical performance and low cost is the main problem.The author studies this problem in combination with actual project requirements.This paper is based on the design process and simulation results of the project.First,this paper introduces some basic principles of antennas which includes some unique electrical performance parameters and antenna array design theory in short-wave antenna design.They are the theoretical basis for the final antenna array design.Then this paper introduces some basic theories of radio wave propagation.This part includes the theory of ionospheric distribution structure and electromagnetic wave transmission mode in shortwave communication.It is the main theoretical basis for the subsequent calculation of beam pointing of the elevation plane.Each project requirement is analyzed in detail.Three antenna units suitable for short-wave antenna arrays have been proposed.They are biconical antenna units,cage antenna units and log-period antenna units.The electrical performance of the antenna which use horizontal polarization and vertical polarization on the actual ground is discussed separately.Finally,the log-period antenna unit using horizontal polarization is determined as the antenna array unit by comparing two polarization modes of three antenna units.The influence of the distance between antenna array units,the height of the antenna and the size of the special ground on the electrical performance of the antenna is studied after determining the antenna unit.Finally,the appropriate value of each paramter is selected to meet the best electrical performance.In order to further improve the gain of the array,a combination unit with double-layered logperiodic antennas is considered.This method can compress the beam width of the elevation plane and increase the gain of the antenna.At the same time,only the upper unit is tilted in order to take into account the difficulty of construction and beam pointing of the elevation plane.A linear receiving antenna array is designed.An improved miniaturized log-periodic antenna is proposed since the array system requires the miniaturized unit.The lateral dimension of the improved antenna meet the requirement of the array.It can be used as a unit for receiving antenna arrays.Then the antenna array in the form of linear arrangement is simulated.The simulation results meet the requirements of the index.This scheme can be used as the receiving antenna array of this project.A new type of fan-shaped transmitting antenna array structure is proposed.It can ensure high gain in the entire frequency band and reduce the active VSWR of the antenna during the scanning of the antenna array by using this method.Then the antenna array in the form of fan-shaped arrangement is simulated.The simulation results meet the requirements of the index.This scheme can be used as the transmitting antenna array of this project.