Research On Tunable Metasurface Aperture Antenna

With the development of information science and technology,wireless communication systems are becoming more and more complex,and their functions tend to be diversified.The antenna with adjustable performance can meet the requirements of the multi-functional wireless communication system for the antenna and can adapt to different working environments.In recent years,metamaterial have attracted the attention of researchers.Because of their unique electromagnetic properties,metamaterials are widely used in the design of antennas.Metasurfaces which are the two-dimensional structure of metamaterials have the advantage of volume.Since metasurfaces have lower profile,they are more suitable for integrated design with antennas.And because metasurfaces can realize the control of electromagnetic waves,metasurfaces can be used to realize antennas with adjustable performance.Based on metasurfaces,this paper carried out research on antennas with adjustable performance.The specific research work includes the following aspects:1.The beam steering antenna based on holographic metasurface is studied.The relationship between the radiation beam direction of the holographic metasurface antenna and the relative dielectric constant of the substrate is derived.The liquid crystal is applied to the beam steering antenna based on holographic metasurface according to the characteristic that the relative dielectric constant of the liquid crystal can be changed by external bias.The proposed antenna structure is given,and the prototype is fabricated.The simulation and measurement results show that the designed holographic metasurface antenna has the characteristic of beam steering.2.The polarization tunable Fabry-Perot(FP)antenna based on metasurface is researched.The combination design of the polarization conversion metasurface and the partial reflection surface of the FP antenna is proposed to realize a high-gain polarization tunable antenna.The designed metasurface structure is given,and the transmission and reflection characteristics of the designed metasurface are analyzed.The structure of the polarization tunable FP antenna based on the metasurface is designed and fabricated.From the measured results,it can be seen that during the frequency range of 10.43GHz to 11.2GHz,the polarization of the designed antenna can be switched between right-hand circular polarization,left-hand circular polarization and linear polarization by rotating the metasurface to different angles.In the process of polarization conversion,the high gain characteristic of the antenna is always maintained.3.The frequency tunable FP antenna based on metasurface is studied.The realization method of frequency tunable FP antenna is analyzed,and a polarization-insensitive metasurface structure with adjustable reflection phase is proposed,which is used to replace the reflection ground of the FP antenna,so that the working frequency of the FP antenna is tunable.The design structure of frequency-adjustable FP antenna based on metasurface is given.The operating frequency of the designed frequency tunable FP antenna based on metasurface can vary from 8.85 GHz to 9.33 GHz.While adjusting the operating frequency,the high gain characteristic of the antenna is always maintained.4.The multi-mode SIW cavity-based metasurface aperture with random radiation used in microwave computational imaging is studied and the radiation field is controlled..The characteristics of the multi-mode SIW cavity are analyzed.Compared with the traditional SIW cavity,the multi-mode SIW cavity has a significantly increased number of internal resonance modes,which is more suitable for the design of the metasurface aperture with random radiation.The design of the metasurface aperture with random radiation based on the multi-mode SIW cavity is given.To further improve the irrelevance of the radiation field,the resonance frequency of each element of the metasurface aperture with random radiation is randomly distributed,and the positions are also randomly distributed.The prototype is fabricated and measured in a microwave dark room.Microwave computational imaging simulation experiment is conducted using the measured data.The simulation results verify the feasibility and effectiveness of the metasurface aperture with random radiation based on the multi-mode SIW cavity.