IEEE MTT-S 2008 International Microwave Symposium Technical Program

Session: WE2A	Theory and Applications of Metamaterials
Chair:	Jan Machac, Czech Technical University
Co-Chair:	David R. Jackson, University of Houston
Abstract:	This session presents analysis and design for various metamaterial structures, including those composed of split-ring resonators, dielectric, and metallic elements. Novel applications such as metamaterial antennas on conformal surfaces are investigated. Novel effects including near-field focusing are studied, and practical devices such as integrated sensors are realized.

WE2A-01	Revising the Equivalent Circuit Models of Resonant-Type Metamaterial Transmission Lines
1119	F. Aznar, M. Gil, J. Bonache, F. Martin, Universidad Autónoma de Barcelona, Bellaterra, Spain
	In this work, it is shown that the previously reported and accepted equivalent circuit models of resonant type left-handed lines, either loaded with split ring resonators (SRRs), or with complementary split ring resonators (CSRRs), need a revision in order to properly account for the different elements of the structures and to accurately describe their behavior. The main relevant conclusion and novelty of this paper is that the already existing models are formally correct, but some of the reactive parameters do not have the physical interpretation given so far. However, these parameters are related to the parameters of the improved models, which are proposed and exhaustively analyzed here for the first time. A comparative analysis of SRR- and CSRR-loaded lines, to the light of these new models, is also included. The results of this work are of interest for the design of CSRR- and SRR-based microwave circuits.

WE2A-02	Coupling of split ring resonators in a mu-negative volumetric metamaterial
1073	J. Machac, J. Zehentner, M. Blaha, Czech Technical University in Prague, Prague 6, Czech Republic
	This paper presents an experimental and theoretical study of the coupling of split ring resonators, and aims to show ways to widen the frequency band of the response of mu-negative metamaterials. The behaviour of these metamaterials is theoretically described in terms of coupled resonant circuits theory. In particular the coupling is studied on pairs of split ring resonators and systems containing the greater number of resonators. Widening of the metamaterial response frequency band is caused primarily by dispersion of the resonant frequencies of the particular resonators, and to a minor extent by mutual coupling. The more particles participate in the tested system, the wider the frequency band of the system response. The requirement to obtain an isotropic medium is taken into account.

WE2A-03	Dispersion Engineered Metamaterial-Based Transmission Line for Conformal Surface Application
1487	M. M. Hashemi, T. Itoh, University of California. Los Angeles, Los Angeles, United States
	In this paper, a novel conformal metamaterial-based transmission line (TL) is introduced and the effect of conformation is investigated. The effect of conformation on 25 unit-cell composite right/left-handed (CRLH) TL is investigated for two situations: slow-wave mode operation and fast-wave mode operation. Sever performance degrading occurs when the structure is operating in the fast-wave mode, unlike the slow-wave mode. These changes are in terms of the leaky-wave radiation characteristics. In this case dispersion engineering is employed to modify the conformal structure such that it provides comparable performance to the planar version.

WE2A-04	2.5-D Stacked Composite Right/Left-Handed Metamaterial Structures Using Dielectric Resonators and Parallel Mesh Plates
1136	T. Ueda¹, N. Michishita², A. Lai³, M. Akiyama¹, T. Itoh³, ¹Kyoto Institute of Technology, Kyoto, Japan, ²National Defense Academy, Yokosuka-shi, Japan, ³University of California at Los Angeles, Los Angeles, United States
	In this paper, stacked structures composed of mesh plates and dielectric layers including 2-D array of dielectric discs are proposed as a new type of volumetric composite right/left-handed metamaterial structure for TE-polarized waves. No band gap condition between right and left-handed bands is designed in order to broaden the left-handed bandwidth by adjusting the aperture size of the mesh. Based on this layered metamaterial structure, a flat focusing lens which operates in free space is designed and fabricated. For a source launched from a small loop antenna, beam focusing through the fabricated finite-cell-layered lens is experimentally confirmed by measuring the field profiles.

WE2A-05	A 3D Isotropic Left-Handed Metamaterial Composed of Wired Metallic Spheres
1573	A. Sanada, Yamaguchi University, Ube, Japan
	A novel structure supporting three-dimensional (3D) negative refractive index are proposed. The 3D structure is composed of an array of metallic spheres arranged in the face-centered cubic (fcc) lattice configuration as in natural molecules, and all the spheres are wired at the center of the lattice. The structure is simple and scalable in frequency. In order to study the wave propagation in the structure, full-wave simulations using HFSS® are carried out. The dispersion characteristics of the structure clearly show that the structure supports left-handed waves as the dominant mode not only in orientation directions but also in the diagonal directions. Parametric studies of the isotropy and homogeneity enhancements on the structural parameters are also carried out to reveal the relation between the structural parameters and the dispersion characteristics.

WE2A-06	A Correlator Sensor Chip Based on the Integration of Meta-materials and Photonic Crystals
1598	C. Lin, I. Mirza, S. Shi, D. W. Prather, University of Delaware, Newark, United States
	In this paper, we utilize advanced artificial materials, namely, photonic crystals and meta-materials, to construct a sensing head with miniaturized antennas as detecting devices and embedded signal channelization for pre-processing. We experimentally demonstrated miniaturized antennas based on meta-materials, as well as, hybrid lattice PhCs and Schottky diodes for RF channelization. To further decrease the size of the system, we also present our initial design and simulation results for a PhC slow wave delay line, which also functions as a waveguide to the channelized signals.

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