Research And Application Of Single-negative Metamaterial Structures In Microwave Circuits

Recently,electromagnetic metamaterials have become more attractive and been investigated by researchers,because of their exotic electromagnetic properties.Compared with conditional electromagnetic materials,the most widely studied left-handed(LH)metamaterials have double negative characteristics of negative permittivity and negative permeability,which can be used to construct a series of unusual electromagnetic componants.As a type of simplified electromagnetic metamaterial strucutres,single negative metamaterials can improve the microwave circuit performance effectively since the have negative permittivity or permeability.In this dissertation,various of single negative strucutres are proposed and investigated,the detailed are summarized as follows:(1)A novel miniaturized ultra-wide-band(UWB)bandpass filter is proposed by employing localized substrate integrated artificial dielectric(L-SIAD)single negative structures,which realizes good out-of-band features with multiple transmission zeros.The operating principle is explained by equivalent circuit model.Furthermore,the proposed filter is manufactured and measured to verify the application of L-SIAD single negative structures for filter miniaturization.(2)A novel branch-line coupler is proposed based on planar spiral inductor single negative structures.The single negative structure is realized by a microstrip line with a stub in spiral form,which has unusual phase shift charateristcs.Using this structure to design branch-line coupler,the simulation and measurement results show that this branch-line coupler has good performance with size reduction and harmonic suppression.(3)A novel three-dimensional(3D)frequency selective surface(FSS)is proposed by employing square waveguide single negative structures.By embedding several kinds of slots in each waveguide wall,since the slots can act as resonators,a compact 3D FSS with a quasi-elliptic bandpass response is realized below the cutoff frequency of the square waveguide.The operating principle is explained by analyzing electric field distributions at resonant frequencies and an equivalent circuit model.What’s more,3D printing technology is applied to explore the feasibility of additive fabrication for this type of 3D FSSs.