Research And Design Of Miniaturized Ultra-WideBand MIMO Antennas

Combining the advantages of high channel transmission rate and overcoming multipath effect of Ultra-Wide Band?UWB?technology with the advantages of multi-input multiple-output?MIMO?technology to become a new communication technology——ultra-wideband-MIMO communication technology.This thesis studies and designs UWB MIMO antennas around UWB MIMO technology and antenna miniaturization methods,and proposes four compact UWB-MIMO antennas with good performance:A compact ultra-wideband log-periodic dipole array?LPDA?antenna with a size of75×45×1.6 mm³ was designed.The LPDA antenna operates from 2.8 GHz to 11 GHz and reaches the UWB level.The LPDA antenna illustrates S₁₁<-15 dB and average peak gain of 7.42 dBi in the operating,and the LPDA antenna has a directional radiation pattern.An eight-port dual-polarized LPDA MIMO antenna for ultra-wideband systems with an antenna size of 195×195×45 mm³ was designed.The simulation results show that the designed UWB MIMO antenna array illustrates a good impedance match(S₁₁<-10dB),isolation between antenna elements more than 40 dB and envelope correlation coefficient?ECC?less than 0.005 in the entire UWB band?3.1-10.6 GHz?.A twelve-port dual-polarized MIMO LPDA antenna for UWB system in a size of240×240×45 mm³ was designed and fabricated.Measured results show that the designed MIMO LPDA antenna exhibits an impedance match from 2.8-11 GHz with nearly S₁₁<-15 dB,high isolation more than 30 dB,directional radiation pattern,average peak gain of6.815 dBi,ECC<0.005 and total active reflection coefficient?TARC?<-15 dB over the whole operating UWB.A compact CPW-fed UWB MIMO antenna with WLAN band-notched characteristic was designed and fabricated.The size of the proposed antenna is 20×36×0.8 mm³.Measured results show that the designed antenna exhibits an impedance match with S₁₁<-10 dB,high isolation better than 15 dB,radiation efficiency are more than 85%,ECC<0.02 and TARC<-30 dB over the UWB band except for the WLAN notched band.A compact eight-port CPW-fed UWB MIMO slot antenna with WLAN band-notched characteristics in a size of 54×54×0.8 mm³ was designed and fabricated.The proposed UWB MIMO slot antenna is manufactured and measured,measured outcome show that the designed antenna exhibits S₁₁<10 dB,high isolation better than 17 dB,radiation efficiencies are more than 74.7%,ECC<0.02 and TARC<-15 dB over the whole UWB band except for the WLAN notched band.