Broadband Low-Profile Dual-Polarized Crossed Dipole Antenna And Its Applications

Multi-standard communication is one of the development goals of future mobile communication.It requires the antenna to have a very wide working bandwidth and can cover multiple frequency bands;miniaturization is the development trend of wireless communication systems,which can save space,weight,cost and benefit landscaping,which requires the antenna to have a small size.In addition,in order to improve the signal-to-noise ratio of the communication system and improve the anti-interference characteristics of the system,the antenna is required to have dual-polarization performance.For these challenges,this paper conducts in-depth research on low-profile,ultra-wideband dual-polarized antennas,and combines its applications to develop a software-defined radio platform and conduct system experimental verification.The main work is as follows:1.The development of wireless communication base station antennas is summarized,various types of antennas commonly used in base stations are investigated,and their advantages and disadvantages are analyzed and explained in detail.Aiming at the research goal of this paper,the structure of artificial magnetic conductor(AMC)and its formation mechanism are mainly analyzed,the equivalent circuit model is established,and the principle of realizing low-profile is analyzed;the related theory of software define radio hardware system is introduced.The characteristics of antenna broadbandization,hardware generalization,dynamic reconfiguration and functional softwareization in this paper are introduced and analyzed in detail.2.A low-profile broadband base station antenna is developed.The AMC structure is used as the reflector,which greatly reduces the height profile of the antenna.At the same time,by adding metal sidewalls,the problem of unstable gain in the antenna band is solved,and stable radiation characteristics are obtained at the same time;the Y-type coupling feed structure and the coupling microstrip line are adopted,which enhance the in-band matching of the antenna and broaden the working bandwidth of the antenna.The experimental results show that the developed antenna has excellent performances such as high gain,low profile,and broadband directivity.The input impedance bandwidth of the unit antenna is 1.66-2.88 GHz(53.7%),the average gain in the working frequency band is 8.54 dBi.The half-power beamwidths of the E-plane and H-plane at 2.2 GHz are 63° and 65.5°;the input impedance bandwidth of the antenna array is 1.51-2.78 GHz,and the in-band average gain is 14.32 dBi.3.A software define radio platform based on Openwifi architecture is built and verified by experiments.Based on the developed high-gain antenna,the hardware equipment and software architecture of the platform were developed,the construction of AP and Ad Hoc software define radio platforms was completed,and the signal power and throughput rate tests of the platform were completed.The platform built has high flexibility,and is suitable for applications in various scenarios through reasonable programming and configuration.