The Research And Design Of Compact And Band-nothed UWB MIMO Antennas

The UWB MIMO antenna has been a research hotspot in recent years,which combines the advantages of UWB technology such as wide working band,large system capacity,high transmission rate and multi-path effect of MIMO technology.In order to avoid the interference between the UWB communication system and other narrowband communication systems in UWB band,it is necessary to study the band-nothed UWB MIMO antenna.At the same time,there is no interference from other narrowband communication systems in some UWB application scenarios.In order to effectively utilize the UWB spectrum resources,it is also of great significance to study the reconfigurable band-nothed UWB MIMO antenna.This thesis focuses on the research of band-nothed and reconfigurable band-nothed UWB MIMO antennas.The research contents and results are as follows:1.Two band-notched UWB MIMO antennas are designed.By loading two pairs of C-shaped parasitic units around tapered microstrip feedline,the first antenna realizes the notch of WIMAX and WLAN band.The first antenna exhibits S12<-15dB,ECC<0.02,radiation efficiency>75%,peak gain difference<2dB,and stable radiation performance over the whole UWB operating band.The second antenna realize the notch of WIMAX,WLAN and X-band downlink band,and the size of it is 33?31?0.8mm~3.The second exhibits S12<-15dB,ECC<0.07,radiation efficiency>70%,peak gain difference<2.5dB and good radiation performance over the whole UWB operating band.2.An UWB MIMO antenna with out-of-band filtering and band-nothed characteristic is designed.The asymmetric step impedance branch is loaded on the antenna feedline,which is equivalent to a low-pass filter and makes S11?-1.5dB after11.5GHz,suppressing the high-frequency passband radiation.Two pairs of inverted C shaped slots are etched on the radiation patch of the antenna to realize the notch of WIMAX and WLAN band respectively.This antenna exhibits S12<-20dB,ECC<0.05,radiation efficiency>80%,peak gain difference<3dB and stable radiation performance over the whole UWB operating band.3.Two compact and reconfigurable band-notched UWB MIMO antennas are designed.The first is a reconfigurable dual band-notched UWB MIMO antenna,its overall size is 25?25?1.6mm~3.By controlling the state of the switch under the structures which realize the notch of WIMAX,WLAN and X-band,the antenna can work in four operating modes:a dual-band notch mode,two single-band notch modes and a UWB mode.It exhibits S12<-15dB,ECC<0.08,radiation efficiency>90%,peak gain difference<4dB,and good radiation performance under the four modes.The second is a reconfigurable triple band-notched UWB MIMO antenna,its overall size is23?30?0.8mm~3.By controlling the state of the switch under the structures which realize the notch of WIMAX,WLAN and X-band,the antenna can work in eight operating modes:a triple-band notch mode,three dual-band notch modes,three single-band notch modes and a UWB mode.It exhibits S12<-15dB under eight modes.It exhibits ECC<0.06 under mode 1,ECC<0.015 under mode 4,and radiation efficiency>80%,peak gain difference<1.7dB,stable radiation performance under both two modes.