| Since Ultra-wide band technologies are introduced for civil use,they become the hot topic for researchers in communication and microwave field because UWB technologies have the characteristics of large information capacity,low Energy consumption and positioning.Nowadays,smart devices have been enter into peoples daily life,industrial production and so on.If UWB antenna technology is integrated into smart devices,it will inevitably greatly promote the way smart devices transmit information.At the same time,it also caters to the demand for large-capacity data at high speed in the current era of big data.However,in the UWB band,there are many existing communication system bands.How to avoid the interference between UWB equipment and other communication systems existing in the UWB band becomes one of the research focuses of UWB antennas.Band notch antennas which are based on this need are designed.Band notch antenna spares the filter structure in the system,which is greatly improving the system intensive degree.Thus,this paper chooses multi-band notched UWB MIMO antenna as research and design contents.This thesis focus the three key points of multi notched band UWB MIMO antenna,and the related theoretical studies and antenna design work were carried out.At present,the emphases of the band notched ultra-wideband MIMO antenna are: miniaturization,multi-notched band and reconfigurable notched band.Based on these three points,this article completes the following work:1.On the basis of learning and studying the technology of miniaturization of antenna,an UWB MIMO antenna with band notched characteristic is designed.The antenna combined the radiation characteristics slot antenna with monopole antenna.Meanwhile the size of this antenna is only 25mm×25mm.After processing and testing,the coupling degree for two ports is less than 15 dB in the whole UWB working band.And the isolation is greater than 20 Db in the frequency band above 5GHz,which is superior to many existing miniaturized UWB MIMO antennas.2.An UWB MIMO antenna with three notched band is designed.The detailed design process of a rectangular monopole microstrip antenna,an ultra-wideband MIMO antenna and a triple-band notched UWB MIMO antenna is given.This antenna elements are placed in a vertical direction to achieve polarization diversity and improve isolation between two ports.The ways of slotting,adding parasitic structures and CSRR are adopted in this antenna to achieve notched bands in different frequency bands.3.Based on the research relevant content of the frequency reconfigurable antenna,a triple band notched UWB MIMO antenna is present.Two band-notched can be switched by using two switches on and off states to achieve the bandpass and band rejection in the notched-band frequency.This antenna can realize the conversion between single notched band antenna,double notched band antenna and triple notched band antenna.The Lshaped slot,C-shaped ring structure and EBG structure are used to realize three different frequency band-notched.The innovation of this antenna is that it can achieve different stop band state changes by simply switching on and off the switch. |
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