Non-symmetry And Unit Thickness Of The Left-handed Materials In Microwave

Left-handed metamaterial (LHMs) is a periodic medium in which both the permittivity and permeability are simultaneously negative. Because their group velocity and phase velocity are in the opposite directions, they have many strange properties. The discovery of LHMs has been regarded as one of the ten most significant discoveries in science community in 2003, and has been the front and focus area in physics and electromagnetics research. Using the freedom of design that metamaterials provide, John Pendry and colleagues showed how electromagnetic fields can be redirected at will and proposed a design strategy in 2006. Later, Physicists at Duke University made a circular cloaking device using a properly designed shell of "metamaterial", which was regarded as a breakthrough of the year.In this paper, the defect effect of negative permittivity metamaterials and the asymmetry of the LHMs are investigated in free space, and the microwave transmittance properties of the Ring Resonators are investigated in a rectangular waveguide for the normally incident microwave.The original works and results of this paper are as follows:1. The defect effect in the two-dimensional and three-dimensional negative permeability metamaterials (NPMs) consisting of hexagonal split ring resonators (SRRs) is investigated in free space. It shows that the introduction of defect breaks the periodic arrays and change the resonance behavior of the NPMs, that is the frequency range of negative permeability can be adjusted by defects, which offers a new methods to fabricate tunable NPMs.2. We investigate the transmission and reflection properties of LHMs with the local asymmetry at X-band frequency range in free space. Experimental results show that two transmission peaks and two reflection dips are exhibited in the presence of the asymmetric configuration of SRRs. Furthermore, the position and intensity of the peaks and dips are significantly dependent on the asymmetry between the SRRs and the wires. In addition, the numerical calculations indicate that two left-handed frequency regions can exist by introducing an alternative configuration of the SRRs to the LHMs, which is in agreement with the experimental results.3. We experimentally investigate the microwave transmittance properties of the Ring...