Research Of Multipolar Antenna

With the rapid development of communication technology,spectrum resources become increasingly scarce.Therefore,more requirements are put forward for the functions of the radio system,and the single-function system no longer meets people's needs.It has become the main research content that can improve the communication rate and efficiency in the limited frequency spectrum space,which also puts forward higher requirements for the antenna located at the forefront of the wireless communication system.Since multi-polarized antennas play an important role in expanding channel capacity and improving the transmission efficiency of the system,the research on multi-polarized antennas is particularly important.Most of the published articles are dual-polarized antennas composed of symmetrical structures,and antennas that realize multi-polarization are relatively rare.This thesis analyzes and studies the polarized reconfigurable antenna based on reconfigurable power splitter and the dual-polarized antenna based on metasurface.The main works are as follows:A miniaturized dual-polarized antenna based on short-circuit loading technology is proposed.The horizontal polarization and vertical polarization of the antenna are realized by the coupling of two vertically placed dumbbell-shaped feed structures and radiating patches.The antenna size is reduced by the microstrip radiation patch gap coupling and short circuit loading structure.After the antenna miniaturization,the volume is reduced to more than 60% of the original.The bandwidth of the antenna is extended by using a double L-type matching network,and the impedance relative bandwidth of the antenna is increased from 4.65% to 8.83%.Finally,the simulation results are verified by processing the antenna.A scheme of multi-directional linearly polarized and double circularly polarized antennas is proposed.Firstly,a reconfigurable power divider with continuously adjustable power ratio is designed by loading a varactor diode.In order to achieve a larger adjustable range of power division ratio,a cascaded power divider method is adopted,and the realized power division ratio(d B(S(2,1))-d B(S(3,1))can be adjusted in the range of-20 d B~+20 d B.On the basis of this power divider,a controllable 90° phase difference is realized by loading a PIN diode and a 90° phase shifter,so that the reconfigurable power divider realizes a controllable power division ratio and phase difference.Furthermore,based on this reconfigurable power splitter as the feed structure of the dual-line polarized antenna,the generation of arbitrary polarized waves can be realized.Several multi-polarized antennas based on metasurface structure design are studied.First,a metasurface structure composed of 4×4 small square patches was designed as the antenna's radiation structure,and a wideband dual-line polarization antenna was realized by using slotcoupled feed mode.The antenna impedance relative bandwidth obtained by simulation is 52.43%,the isolation degree of two ports in the bandwidth is greater than 26 d B,and the maximum gain is 9.2 d Bi.Then a dual circularly polarized antenna is realized based on the metasurface structure of the polarization conversion.Then a dual circularly polarized antenna is realized based on the metasurface structure of polarization conversion,and its bandwidth when < 3 d B is 6.04%.In order to broaden the antenna bandwidth,by adding a layer of metasurface structure on the basis of this circular polarization structure,the bandwidth of < 3 d B is 11.84%,and the maximum antenna gain is 9.6 d Bic.The Xshaped slot polarization reconfigurable antenna based on the polarization conversion metasurface is further designed,and the bandwidth of < 3 d B reaches 19.23%.