Equivalent Electromagnetic Properties Of Metamaterials And Its Application In Miniaturization Of Microstrip Antennas

With the continuous updating of wireless communication systems,and due to the need for reduced antenna size in commercial,medical,military and aerospace fields,conventional antennas must be made toward miniaturization,wideband,excellent performance and high gain.These miniaturisation techniques include material loading,reshaping the antenna,shorting and folding,introducing slots and defects in the ground plane and the use of metamaterials.The major object of this paper is discussion how to achieve at the miniaturization and wideband of microstrip antenna using metamaterials."Metamterials" means a novel kind of aritifical electromagnetic materials with good and excellent performance,metamaterials has been widely used in the microwave cirucuit and design antenna.After loading the metamaterials,the size of patch breaks through the limitation of half wavelength,become an important approach to implement miniaturization of microstrip antenna.Within this paper,the main work and innovation of this thesis is as follows:(a)Learning the relevant knowledge about.metamaterials,master how to design metamaterials strcture,and how to extraction the equivalent permittivity and the equivalent permeability from the S parameters.(b)Discuss the relationship between metamaterial strcture unit cell and the equivalent permittivity and permeability,designs a novel metamaterial structure unit cell.To obtain tri-bands by loading metamaterial structure unit cell of the traditional microstrip antenna,implements a metamaterial microstrip antenna working in low frequency band and miniaturization.(c)The antenna with array conductors is designed,the simulation result show that under the condition of keep resonant in frequency basically unchanged,the antenna dimensions can significantly descend,achieve at the antenna miniaturization.Reduction in size:48.4%.(b)Through loading an air layer between the artificial substrate and the ground plate to broaden the bandwidth,the broadband and miniaturization antenna using metamterials inspired is designed,the bandwidth is increased by 3.98%,which is about 6 times larger than that of original model.(e)Achieving the miniaturization of microstrip antenna using annular concave shape Defected Ground Structure(DGS)and broadening the bandwidth,reducing the resonance frequencies,the simulated and measured results agree very well.