Design And Decoupling Of Dual-band Microstrip Array Antenna

With the development of the fifth generation communication system,the demand of simple element design in global positioning system,satellite communication system and so on is increasing.However,the strong coupling between array elements is always accompanied with the rapid deterioration of antenna radiation performance.Therefore,how to realize dual-frequency antenna and decoupling of array elements with simple element design is a research hotspot with great application potential.This paper focuses on the design of dual-frequency microstrip antenna array and the reduction of coupling between array antennas as follows:1.Two kind of dual-frequency microstrip patch antenna arrays are designed based on the principle of orthogonal mode and the principle of loading electrically resistant load.Orthogonal mode principle can excite two modes simultaneously by feeding at the intersection of excitation points of different modes.In this paper,TM₀₁and TM₁₀modes are excited at the same time by selecting suitable feed points to achieve dual-frequency operation at 3.6 GHz and 4 GHz.Then,a dual-band microstrip antenna array is designed by the chip slotted method based on the principle of loading resistive load.The array works at 2.7 GHz and 4 GHz.Because the coupling phenomenon of antenna array designed by orthogonal mode method is more intense,the research on coupling problem of dual-frequency array antenna will be carried out on this antenna.2.Two kinds of decoupling structures are designed based on bandstop filtering principle and field cancellation principle.First,a defected ground structure（DGS）based on band resistance filtering principle is studied and designed.The band resistance characteristics of DGS at specific frequency is realized by controlling the internal and external radii of the two rings.The structure achieves 28.3 d B and 20.4 d B coupling reduction at 3.6 GHz and 4 GHz,respectively.Then the slot-DGS based on band-stop filtering principle and the half wavelength microstrip resonator based on field cancellation principle are studied and designed,and the machining test is carried out.The experimental results show that the slot-DGS can achieve about 17.2 d B coupling reduction at 3.6GHz,and the half-wavelength microstrip resonator can achieve 22.2 d B coupling reduction at 4GHz.3.A annular slit metasurface structure based on surface wave suppression is designed to reduce the coupling at 4 GHz when the slot-DGS at 3.6 GHz remains unchanged.By analyzing the current vector distribution of the patch and the supersurface coating,it is verified that the supersurface coating provides an indirect coupling field and excites the orthogonal mode of the coupled antenna to inhibit the coupling between the antenna arrays.The coupling reduction is about 19.3 d B and43.5 d B at 3.6 GHz and 4 GHz,respectively.