Design Of UWB MIMO Antenna With Notch Characteristics

The antenna plays an essential role in wireless communication system,and its performance will have a direct impact on the communication system.Ultra-Wide Band(UWB)technology has been widely used in the communication field due to its low cost,strong confidentiality,and high channel transmission speed.However,its signal fading problem is more prominent under the influence of multipath.The combination of Multiple Input Multiple Output(MIMO)technology and UWB can perfectly solve the problem of multipath fading.In the development process of UWB MIMO antennas,how to achieve high isolation on the basis of miniaturization is still a challenge.In addition,it is also particularly important to suppress the interference of narrow-band systems such as Wireless Local Area Network(WLAN),Worldwide Interoperability for Microwave Access(Wi MAX),and X-band used for satellite communications in the UWB range.In order to meet the requirements of wireless communication equipment,this thesis has worked on the miniaturization,isolation and notch characteristics of UWB MIMO antenna,and finally designed three UWB MIMO antennas with notch characteristics.The main work of the thesis is as follows:(1)A high isolation UWB MIMO single-notch antenna based on angle diversity is designed.The antenna integrates the Vivaldi antenna and the UWB slot antenna to improve the space utilization.The difference between the end-fire antenna and the side-fire antenna achieves an isolation of-19 d B between the antennas.In order to suppress the interference of the WLAN frequency band in the ultra-wideband range,the Vivaldi antenna and the UWB slot antenna introduce LCL-shaped parasitic element and slot to achieve notch characteristics.(2)A compact UWB MIMO dual-notch antenna fed by ACS is designed.The antenna is composed of four stepped radiating units.On the basis of coplanar waveguide feeding,an asymmetric coplanar strip(ACS)feeding method is adopted to further realize the miniaturization of the antenna.The four antenna elements are placed orthogonally to each other,and an isolation of-15 d B is achieved without additional decoupling structure.In order to suppress the signal interference of Wi MAX band and WLAN band,L-shaped parasitic unit and LCL-shaped slot are introduced to realize the notch characteristics.(3)A UWB MIMO triple notch antenna based on a quasi-self-complementary structure is designed.The radiating unit of the antenna is a semicircular structure that is "complementary" to the ground,and the use of a quasi-self-complementary structure can better achieve UWB characteristics.At the same time,according to the radiation characteristics of the quasi-self-complementary antenna,the four elements of the antenna are placed orthogonally to each other,so that the adjacent elements and the diagonal elements achieve isolation of-15 d B and-23 d B,respectively.In order to suppress the interference of WLAN band and X-band uplink signal and downlink signal,two L-shaped slots and one C-shaped parasitic unit are introduced to realize the notch characteristics.