The Design Of Metamaterial And Its Application In Ku And C Band Antennas

Metamaterials,as a kind of artificial composite structures or materials,with special physical properties which are not available in nature.Based on its structure with specific design on the key physical size,metamaterials can break through the limitations of natural law,and it has become the research focus in the microwave field for more than a decade.As an important part of the wireless communication system,the antenna has been developed rapidly today,and the requirements for antennas are increasingly.Because of special physical properties,such as negative refractive index,metamaterials could give antenna some improvement in such aspects as miniaturization,frequency band and high gain,and almost no change in the original antenna.Therefore,this paper fully studies the metamaterials,on the basis of the theory and application of the metamaterial unit designed for four,and will they selectively applied to all kinds of conventional antenna to increase the performance of the antenna.Therefore,this paper aims to study the metamaterials.Based on the theory of metamaterials,four metamaterial units are designed,and applied to various conventional antennas to improve the performance of the antenna.Firstly,this paper introduces the theoretical foundation of the metamaterials,including the source of the metamaterials,special electromagnetic properties of the metamaterials,negative permittivity and negative permeability theory,and equivalent parameter extraction method(Nicolson Ross Weir).Then the basic theory of antenna and the detailed description of related performance parameters are given.Secondly,four left-handed materials are designed in this paper,including a singlefrequency band and three multi-band left-handed material units.The key physical dimension of the unit structure is adjusted effectively,which makes the material unit produce LC resonance.And the left-band is produced in the appropriate frequency band.The structure of the left-handed material unit designed in this paper all works under 20 GHz.In the corresponding application,the size of the corresponding left-handed material unit can be reduced and enlarged according to the design needs.Finally,the left-handed material units are applied to the conventional antenna.Through different loading methods,the improvement of the antenna performance is realized.In the fourth chapter,the first antenna loads the design of the left-handed material unit into the medium substrate supporting the microstrip antenna.By loading the metamaterial elements of different numbers,the bandwidth and impedance matching of the antenna are improved to different degrees.The second antenna is a simple planar yagi antenna,the working band is from 5.1 GHz to 7.95 GHz.By loading three metamaterial elements,the gain of the antenna is increased by nearly 1dB,and the antenna gets better impedance matching.The third antenna is a broaband SIW antenna,which working in the Ku band.With the antenna as an antenna unit,a 1*2 antenna array is formed.Insert the deformation unit of the butterfly-shaped metamaterial unit into two antenna units and arrange them in array,the coupling of the antenna is reduced by 11.2 dB.As the above mentioned above,all three antennas show excellent performance in matching,gain,bandwidth and other properties due to the addition of metamaterials.