| The development of satellite communication technology and all kinds of wireless communication technology,put forward new requirements for antenna in the aspect of antenna property like high gain,high anti-interference and low sidelobe.Holographic antenna is a realization of high gain antenna.The conventional holographic antennas commonly utilize the isotropic reference waves by building specific hologram to achieve high-gain objective waves in specific direction.When the hologram adopts concentric circle structure,only normal radiation can be achieved,and it is difficult to obtain high gain due to the existence of open stop-band effect..With the increase of the main lobe direction offset of normal direction on the basis of fixed aperture area,the gain of main lobe decreases rapidly,which makes the antenna aperture efficiency decreases rapidly.Except the reduction of the "equivalent aperture area" is the reason for this phenomenon,the difference in the radiation efficiency of the different-direction aperture caused by the asymmetric hologram is also an important cause of the decrease of the aperture efficiency,which has fully restricted the realization of the high gain antenna property of holographic antenna.In this paper,a new implementation method of holographic antenna is proposed.Based on the spoof surface plasmon polaritons structure,a novel holographic antenna with arbitrary tilt beam and high gain characteristics is designed.The main work and innovations of this paper are as follows:A new implementation method of holographic antenna is proposed.Firstly,a hologram with concentric circular shape is constructed,and the shape of hologram is kept unchanged.Secondly,according to the required beam direction(normal or arbitrary tilt angle),the corresponding reference wave form is calculated to make the reference wave have anisotropic characteristics.Then,the reference wave is utilized to excite the concentric circle hologram,so that the generated objective wave achieves the desired radiation angle,and has the characteristics of high gain and high aperture efficiency.2.Three types of novel two-dimensional linearly polarized holographic antenna are developed.(1)Based on the structure of spoof surface plasmon polaritons(SSPPs)transmission lines,a two-dimensional linearly polarized holographic antenna with circular dielectric substrate is proposed.A central feed structure of "coaxial-microstrip line-SSPPs" is proposed,realized the feed of a two-dimensional holographic antenna.The proposed feeding structure allows energy to transition from the TEM mode in the coaxial line to the quasi-TEM mode in the microstrip line and further smoothly transitions to the complex mode of the SSPPs transmission line.Such an antenna has better radiation performance than a conventional two-dimensional holographic antenna when implementing oblique beam radiation,but is accompanied by bidirectional beam radiation in the upper and lower half spaces.(2)A two-dimensional linearly polarized holographic antenna with cutting dielectric substrate is proposed.After deeply investigating the effect of dielectric substrate width on antenna radiation properties,this paper utilizes cutting dielectric substrate not only solves the problem of bidirectional radiation and achieves half-space single beam radiation,but also greatly increases the main lobe gain.(3)A two-dimensional rotationally perturbed linearly polarized holographic antenna is proposed.On the basis of holographic theory,the gain contribution is small in the near ?=±90° structure.In this paper,the method of rotational perturbation improves the contribution of the perturbation structure near the ?=±90° direction to the radiation field,and thus increases the antenna gain.Finally,the physical object was fabricated and the new method was verified.3.Two types of novel two-dimensional circularly polarized holographic antenna are proposed.(1)Based on the proposed new design method of holographic antenna,a two-dimensional circularly polarized holographic antenna with circular dielectric substrate is proposed.On the basis of two-dimensional linearly polarized holographic antenna with circular dielectric substrate,circularly polarized radiation waves with arbitrary main lobe direction and wide axial ratio bandwidth are realized by utilizing novel method of holographic theory and circular polarization perturbation.(2)After discussing the influence of dielectric substrate width on antenna radiation performance,a two-dimensional cutting-substrate circularly polarized holographic antenna with better radiation characteristics is obtained.Finally,the physical object was fabricated and the new method was verified.4.A one-dimensional linearly and circularly polarized holographic array antenna is proposed.Based on the structure of SSPPs transmission line and the new method of holographic theory,one-dimensional linearly polarized and circularly polarized holographic array antennas with better radiation characteristics are realized by using a one-divided-two power divider. |
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