Researches On Shared-aperture Antenna With Large Frequency Ratio

With the rapid development of communication technology,the fifth-generation mobile communication（5G）has become a global hotspot.The current 5G systems can be divided into two categories in terms of frequency band.The first category operates below 6GHz,which is used for long-distance communication and large-scale coverage.However,its spectrum resources and the bandwidth are limited.The other is the millimeter-wave band with large spectrum bandwidth and high transmission rate.In order to meet the requirements of the above two frequency bands,the multi standard compatible communication systems for microwave and millimeter-wave band has become the future trend.However,the coexistence of multi system is becoming increasingly difficult because of the limited space of the station site and the shortage of space resources.As an important part of the wireless system,the antenna design needs to be able to achieve efficient integration of microwave and millimeter wave antennas in a multi standard system.Therefore,the microwave/millimeter wave dual-band shared-aperture antenna has become a research hotspot of wireless communication system.With the background mentioned above,this thesis mainly studies the methods that can achieve high-performance microwave/millimeter wave dual-band shared-aperture antennas and proposed a variety of large frequency ratio shared-aperture antennas work in microwave and millimeter wave bands.The main work can be summarized as follows:1.Dual-band shared-aperture antenna with large frequency ratio and high aperture reuse ratio and high isolation:To meet the high isolation and miniaturization requirements of dual-band shared-aperture antenna,this thesis started research on the method of realizing high isolation and high aperture reuse rate for microwave/millimeter band antennas.First,a substrate integrated waveguide（SIW）cavity-backed slot antenna array is used for structure-reuse.The millimeter wave band uses the TE₃₁₀-TE₁₃₀ hybrid mode of the cavity backed slot antenna array,while the microwave band uses the TM₁₀ patch radiation mode,which finally realizes the high aperture multiplexing rate（～87.5%）of the microwave/millimeter band antenna.Secondly,a feeding structure with filtering characteristics is used to improve the isolation between different frequency antennas in the microwave frequency band,and finally a high isolation of more than 50dB is achieved.The measured results shows that the proposed microwave/millimeter wave shared-aperture antenna has the characteristics of high isolation and high aperture-reuse rate.This part of work provides a valuable alternative technical scheme for realizing dual-band shared-aperture antenna with high-performance large frequency ratio.2.A dual-wideband shared aperture antenna with large frequency ratio and muti functional:In order to further improve the channel capacity,the research on microwave/millimeter wave dual-wideband shared-aperture antenna with multi-function is carried out.Firstly,the electromagnetic dipole antenna with dual polarization and wideband characteristics is used as the antenna of microwave band.The grounded coplanar waveguide（GCPW）feeding network is used to improve the polarization isolation.Secondly,combined with the idea of partially structure-reuse,the reuse of the electric dipole in the electromagnetic dipole antenna is carried out.The 2×2 MIMO antenna is achieved by fusing the millimeter wave high-order mode SIW cavity-backed patch antenna array on four dipole arms.In order to realize the wideband characteristics of millimeter wave antenna,two SIW high-order modes that can be excited simultaneously with the main mode of the patch are introduced in the working band of the antenna by optimizing the structure of the SIW resonator.The measured results shows that the proposed microwave/millimeter wave shared-aperture antenna combines wideband,dual polarization,MIMO functions,and achieves high polarization isolation.This part of work provides a valuable alternative technical scheme for realizing dual-band shared-aperture antenna with multi-function and large frequency ratio.