Research And Design On Wideband Dual-polarized Antenna And Phase Shifter

With the rapid development of wireless communication technology,antennas as the main components play an important role in the whole communication wireless systems.Especially,the antennas and feeding networks put forward the higher requirements in the spectrum monitoring system.Such as the antennas need to require the following performance: wide bandwidth,dual polarizations,omnidirectional radiation pattern,compact size.Moreover,the feeding networks need to require the following performance: broad bandwidth,low insertion loss,small phase difference.Therefore,designing new antennas and feeding networks for spectrum monitoring system have an important significance.In this thesis,the research and design of the wideband dual-polarized antenna for spectrum monitoring system is mainly elaborated,then we propose a new 90° phase shifter for wideband dual-polarized antenna,finally we introduce a novel wideband dual-polarized omnidirectional antenna for base station and WLAN.The main contributions of this article can be summarized as follows:1.A novel wideband dual-polarized antenna(80-800 MHz)is designed,this antenna has the following properties: a)The antenna can achieve omnidirectional radiation patterns in some particular frequency bands for vertical polarization(VP)and horizontal polarization(HP)respectively;b)Combining Bowtie antenna and monopole antenna in a limited volume,resulting in a compact size;c)The cross dipole not only acts as the radiating element for the HP but also serves as the ground plane for the VP simultaneously;d)Good isolation can be obtained between Bowtie antenna and monopole antenna.2.Feeding network is an indispensable part of antenna systems.The proposed wideband dual-polarized antenna needs to feed with 90° phase difference,thus a new UWB 90° phase shifter based on broadside coupler and T-shaped stub is designed.This design achieves the widest bandwidth,low insertion loss,small phase difference,and low cost.3.Designing a novel wideband dual-polarized omnidirectional antenna for base station and WLAN.The antenna's four Bowtie arms are connected,on the one hand the impedance of antenna can be matched at 50 ohms,on the other hand the radiation patterns of antenna can be improved,and achieved omnidirectional radiation pattern between 1.7-2.45 GHz.