Research And Design Of Holographic Antenna

The position and shape of some satellites are constantly changing with respect to the earth,and the changeable motion state will affect the communication quality between satellites and the ground antenna.Antennas with beam scanning capabilities can solve this problem well.In this paper,the liquid crystal material is used as the medium of the holographic antenna,and its electrical tuning capability is used to realize beam scanning.High gain is achieved by loading a metasurface on the top of the antenna.The specific research content is as follows:1.Research on holographic antenna based on liquid crystal beam scanning.The tunable principle of the liquid crystal medium is studied.The dielectric constant of the liquid crystal can be changed by controlling the bias voltage of the liquid crystal.The reconfigurable characteristics of the antenna pattern can be realized by using the liquid crystal as the dielectric substrate of the antenna.The hologram is obtained by combining the reference wave and the object wave of the holographic antenna by interferometry,and then the original reference wave is used to illuminate the hologram,so that the desired beam can be restored,that is,the characteristic of beam scanning can be realized.The experiment results show that the antenna can achieve beam scanning from-45°to 58°at 12.8 GHz,and the minimum peak gain is greater than 10.3dB,so as to achieve continuous zero-crossing beam scanning of the holographic antenna.2.Research on high gain holographic antenna based on metasurface.The design of the phase gradient metasurface unit is briefly introduced,and a phase gradient metasurface with a size of 179.4×54.6×4.64 mm~3 is designed according to the principle of phase compensation.According to the reversible characteristics of the electromagnetic wave propagation path,thereby increasing the gain of the antenna.The simulation and test results show that the peak gain at 12.8 GHz is increased by 5 dB compared with the antenna without a metasurface.The loading of the phase gradient metasurface can effectively improve the limitation of the low gain of the holographic antenna.