Research And Design Of Ultra-wideband MIMO Antenna With High Isolation

As an important component of wireless communication equipment,antenna is mainly used to receive and send signals,and its performance largely determines the normal communication of the whole system.Ultra-wideband(UWB)technology has the advantages of frequency bandwidth(3.1-10.6GHz),positioning accuracy can reach centimeter level,etc.and can provide positioning accuracy of several centimeters.However,the very low power spectral density of UWB system will lead to the multipath fading problem,which can be converted into advantages by MIMO technology,so as to improve the channel capacity and data transmission rate of the system.The combination of UWB technology and MIMO technology is conducive to the development of current communication technology.Hence,the UWB MIMO antenna with excellent characteristics such as miniaturization,high isolation and multiple notch waves has been widely studied and reported.This article mainly focuses on the miniaturization technology,decoupling technology and multi-notch technology of MIMO antenna.The specific work includes the following aspects:(1)Research and design a miniaturized UWB MIMO antenna with high isolation.Firstly,the symmetric half-cutting method is used to design a compact UWB antenna,which is half the size of the original antenna.Secondly,the antenna is placed in parallel inversion,designed as a two-port UWB MIMO antenna,and a novel fence-type decoupling structure is etched on the bottom of the antenna dielectric substrate,which the isolation of the MIMO antenna in the operating frequency band is obviously improved.The simulation and test results show that the MIMO antenna has a compact structure of 50×35 mm2.good impedance matching and high isolation(S21>25dB)in the 3.0-11GHz operating bandwidth,an envelope correlation coefficient less than 0.004,stable gain,and good radiation effect.(2)Based on the MIMO antenna proposed in(1),an UWB MIMO antenna with dual notch band is designed.Two L-shaped slots with different lengths and opposite directions are etched on the surface of the antenna radiation patch to realize in3.1-3.7GHz and 5.15-5.85GHz notch functions,effectively restraining the interference of WiMAX(3.3-3.7GHz),IEEE802.11a WLAN(5.15-5.825GHz)to the UWB band.The test results show that the MIMO antenna not only maintains the original characteristics of high isolation,but also increases the dual-notch characteristics,and the simulation results are in good agreement with the measured results.(3)Combining the antenna miniaturization technology,decoupling technology and notch technology discussed previously,a four-port double-notch UWB MIMO antenna based on polarization diversity is designed.When no other decoupling structure is added,the decoupling technology of polarization diversity is adopted to make the isolation of the MIMO antenna greater than 20dB in the 2.3-16.3GHz operating bandwidth.In addition,the slot-etching method is adopted to make the antenna have notch characteristics in3.3-3.8GHz and 5.0-5.8GHz two frequency bands,and the interference of the two narrow-band frequency bands of WiMAX and WLAN are suppressed.The UWB MIMO antenna with the characteristics of miniaturization,high isolation and notch proposed in this paper provides more ideas for the selection of antennas in MIMO communication equipment,and has certain reference value.