Optimal Analysis And Design Of Covered Beamforming Array In Half-Airspace

Antenna is a device that receives and transmits electromagnetic waves,which plays an extremely important role in modern radio communication systems.There are many types of antennas,such as dipole antennas,loop antennas,horn antennas,spiral antennas,and microstrip antennas.In most application scenarios,the single-antenna mode can accomplish communication tasks well,but with the increasing requirements of communication technology,people often need antennas with high gain,strong directivity,narrow beam and low sidelobe radiation characteristics in some specific situations.While the single-antenna working mode is difficult to reach the established requirements,the concept of array antenna comes into being.The array antenna is composed of several antenna elements in a certain spatial arrangement,and the antenna elements are independent radiators.Array antenna can be divided into various types according to its distribution,such as linear array,planar array and conformal array.By adjusting the spatial distribution of the array antenna,the number of array elements,the current excitation amplitude and the excitation phase of each element to determine the radiation characteristics of the array antenna is called the analysis problem of the array antenna;conversely,it is called the synthesis problem of the array antenna.As one of the many forms of phased-array antennas,the half-air-covered beamforming array antenna studied in this paper covers many hot issues,such as modern radar,satellite communication and navigation,especially in military communication ground-air platform,which is widely used in fast-running carriers such as drones,self-driving cars,and high-speed rails.The half-air-covered beamforming array requires that its radiation characteristics meets the requirements of maximum gain at least 15dBi above the horizontal plane(?(28)90~o),and at least 4dBi above the top plane(?(28)0~o),and it needs to meet the requirements that the half-power lobe width is less than 15~o and the maximum sidelobe level can be suppressed more than 15dB and achieve the beamforming coverage of 0~o to 360~o in horizontal angle and-90~o to 90~o in pitch angle.In order to achieve the design requirements,this paper will make deep analysis and research from two aspects:the integrated optimization method of array antenna and the design of half-air-covered beamforming array.The key technology to achieve the predetermined radiation characteristics of the array is to optimize the amplitude distribution of unit current excitation in array antenna synthesis.Traditional array antenna synthesis methods,such as the Dolph-Chebyshev and Taylor synthesis methods,can obtain good optimization results on linear arrays,but for circular arrays or conformal arrays with larger size and more complex distribution,in fact,the traditional array antenna synthesis methods have limitations on such optimization problems,and they often cannot obtain accurate results.As a new type of random search algorithm based on bio-group intelligence,Particle Swarm Optimization(PSO)can obtain more accurate results while faces to solve the high-dimensional,non-linear and multi-peak optimization problems,so it is widely used in integrated optimization of array antennas.However,PSO is prone to premature convergence,unstable convergence and easy to fall into local optimal values.In order to solve these shortcomings,this paper proposes an improved PSO based on the standard PSO algorithm for its own iteration process and updating methods,which has been tested by functions,proves that it has better convergence characteristics than the standard PSO algorithm.Meanwhile,in order to realize the beam coverage of the array in half-space,this paper first designs a broadband circularly polarized directional microstrip antenna that meets the requirements of the unit index,and builds a multi-planar spatial stereo-structure array which is constructed based on the principle of layered and partitioned operation.After the feed excitation optimized by the improved PSO,the physical simulation by HFSS analysis software proves that the design meets the requirements of the project indicators.