Isolation Structure Design Of Compact Multiple-element Antenna Array

In recent years,with the multiple input and multiple output(MIMO)technology widely used to improve data transmission rate and network capacity,The application prospects of compact multiple-element antenna arrays are more and more extensive.However,the strong coupling between the antenna elements makes the design of compact multiple-element antennas difficult.In the case of minimizing the impact on the antenna radiation performance,the design of the isolation structure of the compact multiple-element antenna array is a major challenge in this field.Fragment type structure is widely used in the optimization design of antenna structure due to the flexibility of design,and can reduce the coupling between antenna elements in a multiple-element antenna array;many more complex engineering problems have many extreme values,many variables,many goals,etc.Multi-objective Evolutionary Algorithm(MOEA)has better global search capabilities when solving these engineering problems,and it can obtain multiple pareto optimal solutions in a single optimization.It is widely used in antenna design.This article will take the design of compact antenna array isolation structure as the research object,and conduct research from the perspective of the improvement of the method of designing the Fragment antenna isolation structure based on MOEA / D-GO and the metal wall isolation structure.The research content is mainly divided into the following three parts:1.The method of designing fragment-type isolation structure on the back of ground plane is proposed.In this paper,we use MOEA/D-GO to design the isolation structure of a two element MIMO FIFAS(planar inverted-F antenna)array whose antenna element center spacing is only 20 mm,working at 3.71 GHz-3.79 GHz.Compared with other design results,the design presented in this paper has better front-to-back ratio and the stability of the main beam of the pattern,and has the application prospect in fixed satellite communication.2.Isolation structure design of four element antenna array.In view of the influence of the design of fragment-type structure on the antenna design,a new type of high isolation 2×2MIMO antenna array is designed by using this method,which works in 3.42 GHz-3.5 GHz.The designed isolation structure can effectively reduce the mutual coupling between different elements in the antenna array.Compared with the traditional microstrip array antenna mutual coupling suppression technology,the isolation structure makes the isolation of the antenna portexceed 30 dB,improves the front to back ratio of the array and the stability of the pattern.3.Design of antenna array isolation structure for UHF RFID storage system.In this paper,a compact circularly-polarized antenna with the size of 140mm×140mm and working at 902MHz-928 MHz is designed by loading shorting pins.The results show that the element design has good return loss,axial ratio bandwidth and gain.Then,the designed antenna unit is made up of 2×2 antenna array,and a metal wall isolation structure with open slots is used.In this structure,the open slot can be decoupled by using the field cancellation method,and the metal wall itself can also play the role of decreasing part of the coupling.In 902 MHz-928 MHz,the isolation between each element is more than 22 dB,and the gain is more than 12 dBi.This design has the potential which can be applied to UHF RFID storage system.The design results of the isolation structure of the compact antenna array can well verify that the isolation structure design proposed in this paper has good decoupling ability,and several small antenna arrays designed have practical application prospects.The research content can provide new ideas for the design of the isolation structure of the compact antenna.