Research On Miniaturized UWB MIMO Antenna With Band-Notched Characteristics

The ultra-wideband(UWB)MIMO antennas with band-notched characteristics based on research project are discussed in this thesis.In the first part,the related concepts are introduced,the current status and the existing problems are expounded.The research background and significance of the UWB MIMO antennas and the related theories and methods in this thesis are given.The main research contents consist of two parts.The first part is the research on band-notched UWB MIMO antenna based on UWB monopole antenna.The second part is band-notched UWB MIMO antenna based on Vivaldi antenna.The contexts of the research are as follows:1.Research on band-notched UWB MIMO antenna based on UWB monopole antenna(1)Study on the UWB MIMO antenna with dual band-notched characteristicsIn order to meet the miniaturization,high isolation and filtering requirements of the UWB MIMO system for the antenna,“E-plane cut” is used to achieve the miniaturization of the antenna element.The T-shaped branch loaded on the ground is used to reduce the coupling between the elements.The slots etched on the radiating patch are used to achieve filtering characteristics.Based on the simulated results,the antenna prototype is processed and tested.The results show that the operating band of the designed antenna can cover the whole UWB band(3.1GHz-10.6GHz),and the isolation is greater than 15 d B in the frequency band.The envelope correlation coefficient is less than 0.04.Two notched bands are 5.1GHz-5.9GHz and 6.7GHz-7.3GHz.The measured radiation pattern and peak gain are in good agreement with the simulated.The size is 26.0mm×28.0mm×0.8mm,which meets the performance requirements of UWB MIMO antennas.(2)Research on the four-element UWB MIMO antenna with dual band-notched characteristicsThis design achieves high isolation between antenna elements by placing four elements in rotation orthogonally and using defective ground structure.The measured results of the antenna show that the designed antenna has good electrical performance.The impedance bandwidth can cover the whole UWB frequency band.And the isolation between antenna elements is more than 15 d B.The envelope correlation coefficient is less than 0.02.The value of the gain decreases significantly in the notched band,indicating that the designed antenna has good filtering performance.The size of the antenna is only 40.0 mm × 40.0 mm × 0.8 mm.The radiation pattern is stable and fully meets the requirements.Compared with the published results,the antenna size has an absolute advantage.2.Research on band-notched UWB MIMO antenna based on Vivaldi antenna(1)Study on the Vivaldi UWB MIMO antenna with dual band-notched characteristics According to the design requirements of UWB MIMO antennas,a design scheme using Vivaldi antenna as element is proposed.The T-shaped slit structure etched on the ground is used to reduce the coupling between the units and improve the isolation.Dual band-notched characteristics are achieved by loading SRR structure besides feeding line and etching SRR slot in the floor.The results show that the antenna has a working bandwidth of 2.8GHz-10.6GHz,and the isolation is more than 15 d B.Two notched bands are 5.1GHz-5.9GHz and 6.6GHz-7.2GHz.Furthermore,it has stable radiation pattern and gain which can meet the miniaturization,high isolation and filtering requirements.(2)Research on miniaturized Vivaldi UWB MIMO antenna with dual band-notched characteristicsIn order to further realize the miniaturization of the Vivaldi UWB MIMO antenna mentioned above,the design adopts resistance loading technology to widen impedance bandwidth.The efficiency of the antenna is reduced due to the introduction of resistance component.The results show that the impedance bandwidth is 2.6GHz-12.0GHz,isolation is more than 15 d B during the UWB band.The value of the peak gain and radiation pattern are stable through the whole working band except the notched band.The overall size of the antenna is 26.0mm×26.0mm.All results indicate that this chapter proposes a feasible solution for further miniaturization of the antenna.Finally,the research work of this thesis is summarized,and the problems to be solved in the future are proposed.