Metamaterial-based transmission line components and antennas

This dissertation presents applications employing the unique properties of metamaterial-based transmission line structures. Generally speaking, a metamaterial is an artificial structure with unique properties, but the term is most often applied to structures with effective negative permittivity and permeability. This double negativity results in several unique phenomena such as left-handed propagating waves in which the power and phase travel in opposite directions. In the first chapter of this dissertation, a metamaterial-based transmission line structure, or a composite right/left-handed transmission line (CRLH-TL), will be introduced and some basic characteristics and terminology concerning this structure will be discussed. The CRLH-TL is both unique and advantageous because it has a phase constant (beta) that is non-linear with respect to frequency and the relation between beta and frequency can be designed by changing parameters of the structure. This property is very useful in designing circuit components such as resonators and filters, which will be the focus of the second chapter in this dissertation. The CRLH-TL is also unique in that it supports both leaky-wave and guided-wave modes. This property is very useful in designing leaky-wave antennas, which will be the focus of the third chapter in this dissertation.; The subject of the second chapter is metamaterial-based resonators. In this chapter, the behavior of the resonators will be analyzed by utilizing the dispersion diagram for the CRLH structure, with specific attention to properties such as mode-spacing and Q-factor. Several examples of CRLH resonators are demonstrated, such as balanced and unbalanced structures with improved mode-spacing and/or Q-factors and dual-mode structures with increased mode-spacing. Finally, the design principles will be extended to tunable resonators and simple filters.; The subject of the third chapter is two-dimensional beam steering by metamaterial-based structures operating as leaky-wave antennas. Two approaches to beam-steering will be discussed. The first design utilizes a linear array of one-dimensional CRLH-TL leaky-wave antennas and the second design utilizes a planar or two-dimensional CRLH-TL leaky-wave antenna. The scanning capability for both systems will be experimentally demonstrated.