Study On Construction Of Left-Handed Materials And Their Applications In Microwave Engineering

The emergence of the left-handed material (LHM) with simultaneously negative permittivity and permeability has greatly subverted the classical Electromagnetics and the traditional Optics. Their charming and peculiar electromagnetic (EM) characteristics have attracted numerous excellent researchers devoting themselves to such a brand new domain, therefore, great achievements have been gained in correlative theories and engineering applications in recent ten years. Presently, the research on the LHM remains under a state of exploration, and there are still many tasks desired to be complete, including construction of the high performance LHM structures, analysis of the exceptional EM properties of the LHM and their applications to microwave engineering. To this end, we carried out a comprehensive research encircling above aspects.Firstly, a novel LHM with adjustable left-handed passband is proposed, which is constructed by inserting metallic wire array and ferrite into a TE10rectangular waveguide. The mechanism of the adjustable left-handed passband is deeply analyzed. The backward wave property and the negative refraction property are demonstrated by the dynamic field display method and wavefront tracing method, respectively.Secondly, two methods are proposed for retrieving the effective constitutive parameters of the LHMs with symmetrical unit cells. The determination of the boundaries of the effective homogeneous slab, the selection of the correct branch of the real part of the refractive index and the sensitivity of the retrieved constitutive parameters to the accuracy of the S parameters have been taken into account in both methods, causing the two methods to be high in accuracy and stable. Especially, the second method can be applied to retrieve the constitutive parameters of the novel LHM constructed by inserting metallic wire array and ferrite into a TE10rectangular waveguide, which permits us to further analyze the EM properties of the novel LHM structure in the perspective of the constitutive parameters.Thirdly, the ideal composite right/left-handed transmission line (CRLH TL) theory and the method for implementing the practical CRLH TL structure through the LC lumped network are detailed, and the zeroth-and negative-order resonance phenomenon of an open-ended or short-ended CRLH TL section is analyzed deeply. These novel theories can be extension of the conventional TL theory and resonator thoery, and can also be theoretical foundation to construct and analyze the novel TL type LHMs. Fourthly, the EM properties of the CSRR-based microstrip-ε line and left-handed line are thoroughly analyzed. The condition to realize broadband resonant type CRLH TL is discussed in virtue of the lumped equivalent circuit model of the left-handed line. The resonant property of the shunt branch of the lumped equivalent circuit model of the-ε line is exploited to implement a novel lowpass filter with abrupt transition knee, and the nonlinear dispersive frequency response of the left-handed line is utilized to design a dual-band branch line directional coupler.Finally, a simplified CRLH TL (SCRLH TL) structure is proposed. Based on the CRLH TL theory, the novel structure is analyzed in terms of its dispersion and impedance characteristics, which shows the SCRLH TL can produce broadband even UWB impedance matching bandwidth, and such a superior property is used to realize a miniaturized UWB filter with widened upper stopband. In the end, the SCRLH TL unit cell is adopted as a novel zeroth-order resonator to design a novel compact microstrip bandpass filter.