Constructions Of Left-Handed Metamaterials And Their Applications In Microwave Engineering

The emergence of the left-handed metamaterial (LHM) with simultaneously effective negative permittivity and permeability has subverted the classical Electromagnetics and the traditional Optics. The discovery of LHM 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. Compared with traditional materials, electromagnetic waves transmitted in LHM will behave some fantastic characteristics, which have attracted more and more attentions of numerous researchers. However, the research on the LHM is just at its exploration stage, and there are still many tasks need to be complete, including analysis of the exceptional EM properties, construction of the high performance LHM structures and their applications to microwave engineering. The main contributions of the dissertation can be summarized as follows.Firstly, a 2-D planar LHM with broad bandwidth is proposed. Its relative bandwidths are above 61.6% and the unit cell electrical sizes are below 0.095 along two dimensions. The frequency band where the LHM is applicable is tunable. The double negative property, the backward wave property and the negative index of refraction property are verified to prove the existence of the LHM. In addition, the characteristics and typical applications of complementary split-ring resonator (CSRR), which is the dual structure of the 2-D planar LHM, are described. An ultra-wideband filter which is composed of CSRRs etched on the surface of a substrate integrated waveguide (SIW) is proposed. By using the characteristics of CSRRs resonant below the waveguide cutoff frequency, an additional forward passband below the waveguide cutoff can be obtained. So the filter size decreases by 40%, while maintaining the advantages of SIW, such as small size, light weight, easy processing and integration, etc.Secondly, the ideal left-handed (LH) and composite right/left-handed (CRLH) transmission line (TL) theory are detailed. The asymmetric and symmetric CRLH TL networks are compared. Then an asymmetric coplanar-waveguide-based CRLH TL structure with ultra-wideband and a modified symmetric CRLH TL structure are proposed. These structures have planar structure and compact size which make them easier to implement in diverse miniaturized components. Furthermore, the undesired resonances of the interdigital capacitor, due to the multiconductor structure, are removed. Some applications of CRLH structure are presented. For one thing, by analyzing the left-handed and right-handed passband, the mechanism of the application of the CRLH TL in bandpass filter is proposed. Using the symmetric CRLH TL structure, an ultra-wideband filter is proposed, by which the mechanism is confirmed. For another, the principle of leakage radiation is illustrated. The advantages of the CRLH leaky-wave antenna compared with conventional leaky-wave antenna are given: the capability of backfire-to-endfire frequency-scanning and simple feed mechanism. A double-side radiating leaky-wave antenna based on the symmetric CRLH TL structure is proposed. The numerical simulations and experimental measurements are used to confirm the performance of the antenna.Finally, the ideal dual-composite right/left-handed (D-CRLH) transmission line (TL) theory is detailed. A symmetric D-CRLH TL structure is proposed. While a D-CRLH TL is band-stop in nature, a band-stop filter is constructed. Furthermore, by utilizing the presence of parasitic effects, a leaky-wave antenna with backfire-to-endfire radiation capability is proposed. This antenna also has a simple feed mechanism.