Research On End-fire Antenna Based On Spoof Surface Plasmon Polaritons

Surface plasmon polaritons(SPPs)are surface waves formed by the collective oscillation of free electrons on the metal surface.It can only be excited at the interface of two materials with opposite values of permittivity,and propagate at this interface.In the process of forward propagation,the electric field components on both sides of the interface decay exponentially in the vertical direction,and finally decay to the interface,so that the surface wave can be restrained.Therefore,SPPs can't be restricted by the diffraction limit in optics.However,in the natural state,such surface waves only appear in the light frequency and far-infrared frequency bands.Spoof surface plasmon polaritons(SSPPs)can exhibit dispersion characteristics similar to SPPs,and it makes up for the regret that surface plasmons cannot be formed in low frequency bands.In recent years,the research and application of SSPPs has been extended to many microwave components,such as filters,power splitters,antennas,etc.The antenna research of SSPPs mainly focuses on leaky wave antennas,so the research on end-fire antennas is not sufficient.This thesis mainly studies end-fire antennas based on artificial surface plasmons.The specific research contents are as follows:1.A new type Vivaldi antenna based on SSPPs is designed.First,taking 5GHz ? 12 GHz as the working frequency range of Vivaldi antenna.With this design requirement,the feed structure and structure size of the antenna are determined.Then,at the terminal opening of the antenna metal radiation,an elliptical spoof surface plasmon waveguide director structure is added,which can gather electromagnetic waves to increase the antenna gain and obtain good end radiation.Compared with the original antenna,the operating frequency of the antenna is still 5GHz ? 12GHz;the relative bandwidth remains unchanged at 82.3%.In the entire frequency band,the average gain has increased by 2d Bi.The antenna's radiation performance has obvious advantages.2.A log-periodic antenna based on SSPPs is proposed.First,determining the basic structure parameters of the log-periodic antenna with a working frequency range of 7.5GHz to 10.5GHz,such as the length of the first element,the maximum distance between the elements,and three important structural factors.Then,the spoof surface plasmon transmission line is used as the feeder for the logperiodic antenna,and the quarter-arc structure is combined to achieve impedance matching of the antenna.The final result verifies that the S parameter of the antenna is less than-10 d B in the range of 7.3GHz ? 10.6GHz.The maximum value of the antenna gain is 8.3d Bi,and the change trend is the same as the simulation gain curve.The antenna has broadband and end-fire characteristics3.An end-fire circularly polarized antenna based on SSPPs is designed.First,the principle of An end-fire circularly polarized antenna based on SSPPs is designed.First,the principle of the circular polarization antenna is briefly explained.Then,based on the design of the complementary dipole antenna,and combined with the artificial surface plasmon transmission line as the phase shift line to design the antenna.two types directors are used to further improve the antenna radiation performance.Changing the aperture length,half-wave oscillator length and phase shift line length to analyze the change rule of return loss and axial ratio.Finally,the antenna is processed for testing.The measured frequency range where the axial ratio of the antenna is lower than 3d B is10.2GHz?10.9GHz,which is not much in deviation with the simulation results.Compared with existing circularly polarized antennas,the designed end-fire circularly polarized antenna based on SSPPs has high gain.