| Modern wireless communication systems are developing toward miniaturization,multifunction and high integration.As a key part of RF front-end,the miniaturization design of antenna is very important for the system.For the lower frequency band(such as VHF,UHF)system,the miniaturization design of VHF/UHF antenna will help to improve the integration of the whole system due to the long electromagnetic wave length and the large physical size of the antenna.For high-frequency band(such as 5G millimeter-wave frequency band)system,the rapid development of MIMO technology makes the number of antennas increase on a large scale.Therefore,achieving the miniaturization of millimeter wave antenna will greatly reduce the volume of large-scale MIMO array and realize the miniaturization of the system.Based on different application background,miniatured antennas are studied in this paper,and the specific research content includes the following three parts.1.Research on miniaturized dual-band circularly polarized antenna for UHF satellite communication.For the UHF satellite communication system,in order to solve the problem of large physical size of antenna in this band,three kinds of miniaturized sequentialrotation feeding circularly polarized antennas based on different research schemes are proposed.The first one is a miniaturized PIFA antenna based on folding technology,which extends the effective path of the current by bending the radiation-coupled dual inverted-L antenna element,achieving a compact dual-band circularly polarized antenna.The antenna has good electrical performance with a compact size of 0.15 ,which can be used in airborne satellite communication system.The second one is a PIFA antenna loaded with split-ring resonators,which adopts the loading principle of metamaterial.By loading the split-ring resonators in the center of the three elements sequential-rotation feeding PIFA array antenna,the dual-band and antenna miniaturization can be realized simultaneously.The antenna size is only 0.15,which can be applied in the terrestrial satellite receiving system.The third is a miniaturized single/dual band split-ring resonators antenna based on structure-reuse technique.This antenna reduces the number of radiation elements of array antenna by structure-reuse and realizes the miniaturization of four elements sequential-rotation feeding antenna(the size is only 0.115),which is suitable for microsatellite system.2.Research on compact high directivity antenna for C-band secure communication applications.For the C-band miniaturized cubesat system,a miniaturized secure communication antenna based on structure-reuse is proposed,which solves the problem of large antenna volume caused by array design in traditional scheme.The monopole antenna is used to transmit noise signal,and the directional circularly polarized antenna is used to transmit communication signal.By integrating the disk loaded monopole antenna and the sequentialrotation feeding circularly polarized antenna into a single antenna structure,the high aperturereuse is achieved,and the overall size of the antenna can be effectively reduced.Finally,the antenna can achieve secure transmission with adjustable coverage,and the overall size can meet the requirements of miniaturized cubesat system.3.Research on miniaturized broadband dual polarization antenna for 5G millimeterwave terminals.For solving the problem of limited space and difficulty in antenna design due to the small size and high integration of 5G millimeter wave terminal,two kinds of miniaturized broadband millimeter-wave antenna elements for phased array system are proposed.The first one is a millimeter-wave antenna based on capacitance loading and stacked parasitic patch to achieve the wideband and miniaturization of the antenna.This antenna can cover 5G millimeter wave 28 GHz frequency band with a compact size of 0.32.The second is a metasurface antenna based on the patch-cavity feeding.Multi-layer metasurface is adopted here to introduce multi-mode resonance to broaden the bandwidth,and capacitance loading is used to achieve antenna miniaturization.Finally,it can cover the millimeter wave 28 GHz and 38 GHz frequency bands at the same time.It merits the advantages of small size and stable radiation performance,which is suitable for 5G millimeter wave terminal system.Although antenna miniaturization technology has become mature,there are still different requirements for the design of miniaturized antennas for different application systems.This subject proposes a variety of innovative miniaturized antennas for three types of wireless communication systems,including UHF satellite communication system,C-band secure communication system and 5G millimeter-wave terminal system,which solve the problem of larger antenna sizes in traditional solutions and have the application potential in wireless communication. |
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