Researches On Microstrip Decoupling Network For Muti-port Antenna Arrays Based On Eigen-mode Analysis

The development of mobile communication technology is changing rapidly.As the communication systems continuously require higher transmission data rate and larger channel capacity,the communication technology standard is improved every ten years.In the increasingly developed 4G communication technology which has been used for commercial purpose and the next 5G communication standard,multi-input multipleoutput(MIMO)technology has attracted widespread concerns from domestic and foreign research scholars due to its advantages of greatly enhancing the channel capacity without increasing the transmission bandwidth and transmission power.Being an important part of MIMO technology,multi-antenna technology has aroused a lot of research interest in recent years.In the trend of miniaturization of mobile terminal equipment,the mutual coupling between compact antenna arrays is a difficult problem to be solved.This paper proposes a systematic theoretical design method to solve the coupling problem between array elements.The simple microstrip line is adopted to constitute the feed network to research on the decoupling method of multi-port antenna arrays.Firstly,the paper elaborates the research background of multi-antenna array decoupling and its significance,and summarizes several commonly used array decoupling methods and the research situation of each method,such as electromagnetic bandgap structure,defective ground structure,neutralized line and decoupling network.Then,the basic theory correlated to antenna is described,including the main electrical parameters of antenna,the mutual coupling between antenna arrays and its analysis method.Meanwhile,the impedance matching principle of parallel single-stubs and the theory of multi-antenna MIMO technology is expounded.Secondly,the paper presents a microstrip decoupling network design method based on the theory of matrix eigen-mode.The two-element antenna array is studied at first,and the detailed analysis of microstrip decoupling network using eigen-mode theory is given.Based on the process,an example of microstrip decoupling network for monopole antenna array is designed.Then,according to the two-element antenna array decoupling network,decoupling networks of three-element linear antenna array for both neighboring elements and all elements are proposed,respectively.Especially,the neighboring elements method adopts microstrip antenna array,and the all elements method adopts monopole antenna array.This theory is verified by circuit simulation and electromagnetic simulation,and the example of microstrip decoupling network of three-element linear monopole antenna array with all elements decoupled is designed.Finally,the paper proposes the design of microstrip decoupling network for centrosymmetric circular antenna array based on eigen-mode theory.The three-element circular monopole antenna array and the four-element circular monopole antenna array are analyzed as the example,respectively.The proposed microstrip decoupling network of three-element circular antenna array is verified by circuit simulation and electromagnetic simulation,and the example of microstrip decoupling network of threeelement circular monopole antenna array is given based on the simulation results.While the effectiveness and feasibility of microstrip decoupling network of four-elment circular monopole antenna array is proved by using the circuit simulation.