High Gain Beam-Control Antennas Based On Electromagnetic Metasurface

Artificial electromagnetic meta-surface is a kind of artificially designed surface structure,it has the characteristics of modulating electromagnetic waves and it has become a hot research topic in the field of international physics and electromagnetic in recent years due to its application in the field of wireless communication and multi-channel communication transmission.Artificial electromagnetic meta-surface is mainly classified into electromagnetic metamaterial,metamaterial with near-zero refractive index and frequency selective surface.Electromagnetic metamaterial with negative permittivity is named as negative permittivity electromagnetic metamaterial,electromagnetic metamaterial with negative permeability is named as negative permeability electromagnetic metamaterial,electromagnetic metamaterial with negative permeability and negative permittivity is named as double-negative left-handed electromagnetic metamaterial.Metamaterial with near-zero refractive index is divided into single near-zero refractive index metamaterial with near-zero permittivity,single near-zero refractive index metamaterial with near-zero permeability,and double near-zero refractive index metamaterial with both near-zero permittivity and permeability.Frequency selective surface is divided into reflective frequency selective surface,transmission frequency selective surface and absorbing metamaterials.Among them,reflective frequency selective surface is divided into partially reflective frequency selective surface and total reflective frequency selective surface.In this dissertation,beam deflection with high gain performance of antenna elements and antenna arrays are innovatively realized based on metamaterial with near-zero refractive index,partially reflective frequency selective surface and transmission frequency selective surface.In addition,beam deflection and high gain performance of electromagnetic vortex wave carrying orbital angular momentum is also achieved to increase the utilization efficiency of communication spectrum.Furthermore,the design of artificial electromagnetic meta-surface based on transparent conducting oxides is researched and explored in this dissertation,a broadband absorbing metamaterial is designed based on transparent conducting indium tin oxide,the growth and fabrication of transparent conducting zinc oxide nano structures is realized.The research contents and creative results of this dissertation are mainly divided into the following parts: 1.High gain enhancement of micro-strip antenna based on metamaterial with near-zero refractive index.Firstly,a novel single near-zero refractive index metamaterial with near-zero permittivity is designed and placed on top of a micro-strip antenna element to realize the convergence of electromagnetic beams and greatly enhance the gain near the near-zero refractive index frequency point.On the basis of the structure of the new single-near-zero refractive index metamaterial,a new dual-band near-zero refractive index metamaterial is designed and realized by further structure optimization.The first near-zero refractive index frequency point of the dual-band near-zero refractive index metamaterial has the characteristic of near zero permeability and the other near-zero refractive index frequency point has the characteristic of near zero permittivity.The dual-band near-zero refractive index metamaterial also has the characteristic of band-stop frequency selectivity.The dual-band near-zero refractive index metamaterial is placed above a micro-strip antenna element to achieve high gain enhancement within a certain bandwidth near the near-zero refractive index frequency points.Based on the structure of the proposed dual-band near-zero refractive index metamaterial,the parameters are optimized to lower the dual-band frequency of the dual-band near-zero refractive index metamaterial compared to the original dual-band near-zero refractive index metamaterial.Cascading the original dual-band near-zero refractive index metamaterial and the dual-band near-zero refractive index metamaterial working at lower frequency,and then place the cascaded structure on top of a micro-strip antenna to achieve significant high gain enhancement in a wide band.The maximum gain enhancement is 6 dB,and the corresponding 3-dB gain bandwidth is 15.07%.Compared with the antenna loaded with the single-layer dual-band near-zero refractive index metamaterial,the maximum gain is increased with the 3-dB gain bandwidth reduced.2.Partially reflective frequency selective surface can be referred to as partially reflective surface,design partially reflective surface to achieve high gain beam deflection micro-strip antenna elements and high gain beam deflection antenna array based on leaky wave antenna principle.Firstly,a wideband partially reflective surface unit with reflective phase positive correlation of frequency is designed,the units with uniform size are then arrayed in a partially reflective surface,and placed on top of an L-shaped probe fed micro-strip antenna to achieve 20.6% 3-dB broadband high gain performance based on the Fabry-Perot resonate cavity principle,the maximum gain enhancement is 6.45 dB.To further improve the antenna gain and the aperture efficiency,two kinds of partially reflective surface unit are designed and arrayed as a non-uniform surface based on Fabry-Perot resonate cavity principle and phase compensation principle,and the non-uniform surface is placed on top of a micro-strip antenna element to achieve a maximum gain enhancement of 9.4 dB and a large aperture efficiency of 54%.The corresponding 3-dB gain bandwidth is 7.3%.Compared with the uniform surface,the non-uniform surface can achieve larger gain enhancement and higher aperture efficiency,but the 3-dB gain bandwidth is relatively reduced.On the basis of high gain enhancement realization,a partially reflective surface is designed to achieve beam deflection.Firstly,cross-shaped and square-ring-shaped partially reflective surface units are designed.Phase coverage of 180 degrees and 80 degrees can be achieved by varying the physical size of the two kinds of units,respectively.Design phase gradient surface based on cross-shaped partially reflective surface unit and square-ring-shaped partially reflective surface unit,respectively,to realize large angle beam deflection with high directivity.An one-dimensional linear micro-strip antenna array is designed and loaded with a non-uniform surface to achieve high gain performance.The non-uniform surface consists of two kinds of units,cross-shaped and square-ring-shaped units.And then a two-dimensional linear array loaded with a partially reflective surface is designed to realize dual-band dual-polarization shared aperture antenna array with beam deflection and gain enhancement at lower frequency.A circularly arranged micro-strip antenna array is designed to generate electromagnetic vortex waves carrying orbital angular momentum.An electromagnetic bandgap structure consisting of multi-layer dielectric substrates and single-layer frequency selective surface are loaded on top of the antenna array to realize high-gain vortex waves and increase the spectral efficiency.The antenna array is fed by Wilkinson power divider.Furthermore,a circular antenna array is designed to generate vortex beams carrying hybrid mode orbital angular momentum.Wilkinson power divider andButler matrix power divider are designed to feed the circular antenna arrays generating vortex beams carrying hybrid mode orbital angular momentum.A phase gradient surface is applied on top of the circular antenna array to achieve high gain,single beam deflection of electromagnetic vortex waves.3.A transmission frequency selective surface can be referred to as a transmission array,The beam deflection of a horn antenna,beam deflection of electromagnetic vortex beam carrying orbital angular momentum generated by an antenna array,and beam deflection of vortex beam are realized based on the transmission array.A transmission array unit is designed to have 310 degree transmission phase variation range with the physical dimension varying,the unit is then arrayed as a transmission array based on the phase compensation principle to realize beam deflection.The transmission array is then loaded on top of an antenna array generating the electromagnetic vortex wave carrying orbital angular momentum to achieve beam deflection of vortex wave carrying orbital angular momentum.Finally,a transmission array unit is designed to have 360 degree transmission phase variation range with the physical dimension varying,and then the unit is arrayed as a transmission array to achieve beam deflection of vortex wave carrying orbital angular momentum.4.The design of artificial electromagnetic meta-surface based on transparent conducting oxides.Design and construct a broadband absorbing metamaterial consisting of two layers of transparent soda lime glass dielectric substrates and three layers of patch-shaped transparent indium tin oxide films.The material can achieve more than 85% absorption in the broadband from 6.1 to 22.1 GHz,and has high optical transparency and wide angle incident wave stability.Fabricate and grow transparent conducting zinc oxide nano structures paves a way for the further design and fabrication of nano structure based artificial electromagnetic meta-surface.