Design And Application Of Compact UWB MIMO Antennas

The multiple-input-multiple-output(MIMO)is considered as one of the most promising technologies,which can meet the requirements of wireless communication systems for large capacity,high spectrum utilization,and resist mutual interference between signals.Based on the ultra-wideband(UWB)technology and the multiple-input-multiple-output(MIMO)technology,the design of ultra-wideband MIMO antennas is researched.Finally,four compact high-performance ultra-wideband MIMO antennas are proposed.1.An ultra-wideband MIMO antenna with off-center feed has been designed.The antenna was printed on an FR4 dielectric substrate with a dielectric constant of 4.4.The whole dimensions of the antenna are 28×31×0.8 mm~3.This antenna achieves an isolation higher than 15dB,partial higher than 40dB,over the impedance bandwidth.The antenna mainly adopts a ground-defect structure method combined with slot coupling,and the current distribution of the radiation patch is changed by the coupling of the floor and the radiation patch to achieve the high isolation required by the ultra-wideband antenna.And,the WLAN band-nothed is achieved by etching the G-shaped groove on the patch,which meet the requirements of the proposed MIMO antenna.2.A coplanar waveguide(CPW)UWB-MIMO antenna,which is fabricated by FR4 substrate material with 0.8 mm thick and 4.4 relative dielectric constant.The whole dimensions of antenna are 27×27 mm~2.The antenna almost has higher than 20dB isolation operating in 2.8-12GHz frequency range.The vertically placed antenna elements to increase the separation between the antenna elements.The current coupling of the current to the surrounding floor gap is used to improve the impedance matching of the antenna.3.The third and fourth antennnas are antiparallel CPW antennas.which are fabricated by FR4 substrate material with 0.8 mm thick and 4.4 relative dielectric constant.These antennas use the spatial position distribution to keep the antenna port away from the other one.The dimensions of third antenna are 25.5×25.5 mm~2.The antenna almost has higher than 20dB isolation operating in 2.8-14GHz frequency range.By etching two square grooves on the diagonal edge,the isolation degree of the antenna in the frequency band of 3-14GHz can reach and even exceed 20dB.The dimensions of fourth antenna are 26×13 mm~2.The antenna almost has higher than 16dB isolation operating in 3-14GHz frequency range.