Research On Microstrip Array Antenna Decoupling Methods

Microstrip antennas are widely used in modern wireless communications due to their small size,light weight,and low processing costs.With the continuo us development of mobile communication technology,a single antenna often cannot meet the high performance requirements,so the antennas need to be arrayed to obtain high gain.However,when a microstrip array antenna is in operation,surface waves are fiercely generated on the surface of the dielectric substrate,which leads to an increase in mutual coupling of the antennas and deteriorates the radiation performance of the antenna.In this paper,by analyzing the mutual coupling effects between the microstr ip antenna array elements,a square electromagnetic band gap structure,a compact electromagnetic band gap structure with a surface etched slot,and a first iteration fractal cross defected ground structure are designed to suppress mutual coupling.The main research contents of this article are as follows:A rectangular microstrip antenna was designed based on the analysis method of the transmission line model,and the mutual coupling between the E-plane and H-plane of the microstrip antenna was studied.Based on the finite element model,the dispersion effect of the surface wave propagating on the mushroom periodic structure was simulated,and the frequency dispersion effects of the surface wave phase variations in the Bril ouin region was obtained.A square electromagnetic band-gap structure with a band gap containing the operating frequency of the antenna was accurately designed,and the decoupling effect of this structure on the E-and H-planes of the microstr ip antenna was verified.The results show that the mutual coupling of the E-plane is reduced by 15 d B while the H-plane is not significantly reduced.In order to further reduce the size of the electromagnetic band gap structure,a compact electromagnetic band gap structure with a surface etched slot was designed on the basis of the square electromagnetic band gap structure,and the unit size was reduced by 9.4%.In addition,the mutual coupling of the E-Plane of the microstrip antenna is also reduced by 17 d B.Based on the fractal theory,an iterative of the fractal cross defected ground structure is designed.The symmetrical open-ended microstrip line method is used to determine the band stop area of the defected ground structure.The periodically cascaded structure is etched on the ground plane to reduce the mutual coupling of the antennas.The simulation results show that the maximum mutual coupling of the Eplane of the microstrip antenna is reduced by 5.4d B.