Research And Design On Compact MIMO Antenna Based On Metasurface For Micro Base Station

As mobile communication system developed rapidly,the fully deployed 4G and the upcoming 5G will certainly face many problems,such as insufficient spectrum utilization and channel capacity.However,traditional base stations are gradually difficult to meet this demand.At present,micro-base stations are used as the supplement of base stations.As an indispensable component in mobile communication,antenna plays a decisive role in the operation of micro-base station system.At the same time,the application of MIMO technology makes the antenna not only ensure miniaturization,but also need to achieve higher isolation requirements,so as to make the antenna element work independently in the whole system.Therefore,the research of micro-base station MIMO antenna with miniaturization,high isolation,broadband has a favorable development foreground.The frame and the primary coverage summary of this studies is as follows:1.In order to solve the coupling problem of the current micro-base station MIMO antenna,a dual-polarized antenna with metasurface isolation wall is proposed.The dual polarization antenna is used as the element to realize the high element port isolation characteristics.Meanwhile,the magnetic coupling feeding network and the bottom inductive circular slot are adjusted to make the impedance matching of the antenna,these methods can ensure that the antenna has sufficient working bandwidth.In addition,a single-layer concave closed-loop metasurface isolation wall structure was loaded between the MIMO antenna element ports,and its frequency selection characteristics are utilized to suppress the spatial waves generated between the elements in the working frequency band,thus effectively improving the isolation performance of the antenna elements.2.In order to further improve the performance of the MIMO antenna element port,to make sure that the antenna array has good performance about high isolation,this article designed a ±45° polarized micro-base station MIMO antenna,the antenna has the characteristics of compact structure and high isolation.By using magnetic coupling feeding network and "H" slot on the floor,the isolation of antenna element port is improved.Besides,the bandwidth of antenna is increased by meandering technology.Between the elements,the two layer asymmetric metasurface isolation wall structure and the rectangular slot structure are used to suppress the spatial and surface wave interference,so as to improve the isolation of the elements.The simulation and test resultsshow that in the working frequency band of 2.5GHz-2.7GHz,the reflection coefficients of each port are less than-15 dB,and the isolation is greater than 30 dB,which ensures the independent work of the element.3.In order to meet the antenna development trend of antenna miniaturization and broadband,a broadband dual polarization micro-base station MIMO antenna is designed on the basis of the two chapters above.The antenna uses the symmetrical magnetic coupling feed network to feed the radiation patch,which improves the stability of the antenna.Besides,by introducing a parasitic square patch,the radiation characteristics and isolation of the antenna are improved.The simulation and test results show that at the band of 2.45GHz-2.8GHz,the impedance of the antenna is well matched and the isolation of the two ports is greater than 40 dB.In addition,the single layer concave closed loop matasurface isolation wall can reduce the coupling between MIMO antenna elements by its space wave suppression.