Simulation Design Of A Low-Profile,Ultra-wideband Dual-Polarized Antenna

With rapid advance of wireless communication system,ultra-wideband technology has attracted considerable attention with the advantages of strong anti-interference ability,high transfer rate and large capacity of system,and promotes the research of ultra-wideband antenna.Dual-polarization technology can not only increases channel capacity,but also reduces the multipath effect,which has been applied extensively in antenna field.Nowadays,communication device is advancing to be smaller,so the compact structure of antenna should be considered during the design process.Low-profile dual-polarized UWB antenna has all the features described above,which is of great practical value in many fields.In this paper,two types of low-profile dual-polarized UWB antenna in L?X band are designed,which are Vivaldi antnna and self-grouned antenna.The Vivaldi antenna includes miniaturized Vivaldi antenna and miniaturized dual-polarized Vivaldi antenna.The self-grounded antenna includes combined antenna,self-grounded bow-tie antenna and dual-polarized self-grounded bow-tie antenna.The main contents of this dissertation include:1)In view of conventional Vivaldi antenna,the effects of several relative parameters on the antenna performance are studied,and a conventional Vivaldi antenna operating at1.95?9GHz is designed.Then exponential tapered slots with circular end are introduced to broaden the lower frequency band and improve the radiation pattern.The dimension of this antenna is 80mm×78mm×1mm.The simulation shows that the operating bandwidth covers the band from 1.19GHz to 9GHz(|S₁₁|<-10d B).In addition,its gain within operating bandwidth ranges from 2.5 to 8.7d Bi,and the radiation characteristic is good.2)A dual-polarized Vivaldi antenna consisting of two proposed antennas is designed.The identical two antenna elements are placed orthogonally in perpendicular direction,and the microstrip lines are adjusted to ensure the integrity of the feeding structure.The overall size of the antenna is 80mm×80mm×78mm?The simulation shows that the operating bandwidth covers the band from 1.2GHz to 9GHz(|S₁₁|<-10d B),and the isolation between two ports is better than 23d B.In addition,its gain ranges from 2.5 to 8.4d Bi with good radiation performance.3)An electric-magnetic vibrator combined antenna with self-grounded structure is designed,with a operating bandwidth of 1.31?9GHz,and its dimension is118mm×38.6mm×116mm.To reduce the height,a low-profile self-grounded bow-tie antenna is proposed with combination of self-grounded structure and bow-tie antenna,and the impact of radiation arm's structure on the performance of the antenna is also studied.In order to achieve balanced feed and impedance transformation,an exponential tapered microstrip balun in bending form is proposed,which exhibits a good transmission characteristics in the frequency band from 1GHz to 9GHz.The overall size of the antenna loaded with balun is 78mm×50mm×48mm?The simulation shows that the operating bandwidth covers the band from 1.24GHz to 9GHz(|S₁₁|<-10d B).In addition,the gain ranges from 2.3 to 8.2d Bi,and the radiation pattern is good.4)Based on the above self-grounded bow-tie antenna,a pair of radiation arms is placed orthogonally on the ground,so a dual-polarized self-grounded bow-tie antenna is accomplished.Considering the particularity of the dual-polarized feed structure,the balanced end of the balun is modified so as to feed the dual-polarized self-grounded bow-tie antenna.The overall size of the antenna loaded with balun is 81.4mm×81.4mm×50.8mm.According to the simulation results,the operating bandwidth covers the band from 1.24GHz to 9GHz(|S₁₁|<-10d B),and the isolation between two ports is better than 26d B.In addition,its gain ranges from 1.1 to 7.1d Bi.