Electromagnetic Characteristics Of Metamaterials And Application In Microwave Circuit

Metamaterials are new structured materials with negative permittivityor negative permeability or simultaneous negative e andμ. In this paper, someelectromagnetic characteristics of metamaterials and application in microwavecircuit are studied thoroughly.Inversed Doppler shift of a moving object in dispersive left-handed materialsand microwave Cerenkov radiation in uniaxial metamaterials are investigated exactly.Numerical simulations are also performed with finite-difference time-domain(FDTD) method. Some new electromagnetic characteristics of metamaterials werestudied. For example, the great dispersion of metamaterials will influence thedirection and magnitude of Doppler shift, as well as, the band width of thereflectance signal; Obtuse angle Cerenkov radiation will be emitted by chargedparticles moving in uniaxial metamaterials.The characteristics and application in microstrip circuit of complementarySplit-Ring Resonator (CSRR) are studied in this paper. CSRR etched in the groundplane provide a negative effective permittivity to the structure. Equivalent circuitmodels for two kinds of CSRR coupling to the microstrip line and extraction methodof circuit parameters are presented. Based on this equivalent circuit models, theCSRRs are applied in the designs of low-pass, high-pass and band-stop microstripfilters. A new type of microstrip directional Coupler with CSRR is proposed in thispaper. The results of simulation and measurement show that the new couplerachieves a high degree of coupling over a wide frequency band.In this paper, the characteristics and application in microstrip filter and couplerof novel defected ground structures (DGS) are presented. It is difficult to obtain widefrequency band for traditional band-pass filter with open-loop resonators. The open-loop DGS resonators can increase the coupling coefficient between theresonators and can be used to design wide-band band-pass filters. A new method toimprove the band width and coupling degree of traditional microstrip coupler usingthe DGS technology is also presented.The research at metamaterials in THz range is just beginning. In this paper, thefrequency selective surface (FSS) in THz range based on metamaterials isinvestigated and simulated with FDTD method.