We present a metamaterial substrate designed to act as a high impedance thin slab that can be used to integrated lowprofile (subwavelength thickness) antennas in components or packages. A transverse equivalent network (TEN) model accurately describing the reflection properties of the impedance substrate is also provided to facilitate its design. Then, we develop a low profile planar antenna consisting of a printed dipole located on top of the parallel metamaterial substrate. The high impedance of the substrate permits to locate the metallic dipole very close to the substrate itself without inhibition of the dipole radiation. The substrate prevents radiation from traveling across the substrate, resulting in a low profile antenna with high efficiency, even though the antenna system is integrated on top of a lossy structure. Two possible feed structures for the dipole over the impedance surface are considered, and simulation data are presented to illustrate their respective performance. © 2009 IEEE.

A metamaterial, arranged by stacking layers of planar constituents suitably shaped to be responsive to arbitrarily linearly polarized incident waves is here shown to exhibit 2D-isotropic effective negative refractive index (NRI). The general concept underlying this metamaterial design consists of closely pairing two metallic particles to accomplish, as a result of their tight coupling, both symmetric and antisymmetric resonance modes, whose proper superposition can lead to an effective negative refraction response. The proposed structure is composed by layers of periodically arranged pairs of face coupled loaded tripoles printed on the opposite sides of a single dielectric substrate. Through a comprehensive characterization of the transmission properties of such metamaterial, together with the analysis of its dispersion diagram, conclusive evidence that the medium exhibits effective NRI properties as well as good impedance matching to free space is provided. We also describe some guidelines to design the proposed metamaterial with a prescribed operational frequency bandwidth, dependently on the structure parameters. (C) 2009 Optical Society of America

In this paper we analyze the propagation through a metamaterial in planar technology recently proposed. The metamaterial basic constituent cell consists of a pair of tightly coupled conductors that supports two main resonance modes corresponding to either a symmetric or an antisymmetric current distribution in the pair. We present an equivalent X-shaped lumped circuit network to be interposed in the transmission line (TL) model of propagation across a metamaterial layer to reproduce its electric and magnetic resonances. We show that reflection and transmission features of a periodic array of dogbone pairs as well as its dispersion diagram are accurately predicted by this simple but effective model. © 2010 IEEE.

The distinctive features and properties of metamaterials containing the constitutive particles composed of tightly coupled pairs of the dogbone shaped conductors and planar spirals are discussed. The results of the full-wave simulations and measurements of the scattering characteristics of such arrays will be presented to illustrate the main concepts of such artificial media. © 2009 IEEE.

Modern nanochemistry has developed efficient techniques to manipulate nanoscale objects with a highly advanced degree of control. Chemically- engineered nanoparticles can be synthesized with a large choice of sizes, shapes, constituent materials and surface coatings, and further assembled spatially into self-assembled structures, either spontaneously or in a directed manner [1]. Advances in particle self-assembly and the quasi unlimited range of nanostructures with controlled architectures and functions available suggest that such assemblies may also provide a simple route to metamaterials at infrared and visible length scales. Indeed, nanochemistry and self-assembly strategies are able to inexpensively produce materials whose inner structure is natively in the right range of sizes for optical and infrared applications and can provide fully three-dimensional (3D) structures, thus opening the way to the fabrication of 3D-metamaterial samples of finite volume of the highest importance to many applications. Such metamaterials may be used, for example, to create 3D homogeneous, isotropic negative index materials (NIMs), with simultaneously negative permittivity and magnetic permeability, cloaking devices or light-based circuits manipulating local optical electric fields rather than the flow of electrons. © 2010 IEEE.

We present a fully printable effective negative refractive index (NRI) metamaterial responsive to arbitrarily linearly polarized incident waves. The proposed metamaterial is composed of a periodic array of tightly coupled Jerusalem cross conductor pairs printed on the opposite sides of a dielectric substrate. Each pair supports both symmetric and antisymmetric resonance modes, whose superposition can lead to an effective NRI of the composite medium. A thorough characterization of the transmission properties of such metamaterial is performed, and conclusive evidences of the medium exhibiting effective NRI properties and impedance matching to free space are presented for a range of the structure parameters. © 2006 IEEE.

We present a lumped circuit description of a novel metamaterial layer made of arrayed pairs of tightly coupled conductors (dogbones or Jerusalem crosses). This lumped element network is synthesized to exhibit the same frequency response of the metamaterial layer when inserted in the plane-wave equivalent transmission line. The metamaterial and its transverse equivalent network (TEN) model is then applied to the design of a high impedance surface for low profile dipoles and a partially reflective superstrate for highly directive Fabry-Perot cavity antennas. Numerical results illustrating the radiation properties of such antennas are provided.

Spherical nanoclusters (NCs) with a central dielectric core surrounded by several satellite plasmonic nanospheres have been recently investigated as aggregates supporting electric and magnetic collective resonances. Notably, the collective magnetic resonance has been exploited to provide magnetic properties in optics, i.e., materials with macroscopic relative permeability different from unity. The NCs discussed in this paper can be realized using state-of-the-art nanochemistry self-assembly techniques. Accordingly, perfectly regular disposition of the nanoplasmonic satellites is not possible and this paper constitutes the first comprehensive analysis of the effect of such irregularities onto the electric and magnetic collective resonances. In particular we will show that the peak of the scattering cross section associated to the magnetic resonance is very sensitive to certain irregularities and significantly less to others. It is shown here that "artificial magnetic" properties of NCs are preserved for certain degrees of irregularities of the nanosatellites positions, however they are strongly affected by irregularities in the plasmonic nanosatellites sizes and by the presence of "defects" caused by the absence of satellites in the process of self-assembly around the dielectric core. The "artificial electric" resonance is instead less affected by irregularities mainly because of its wider frequency bandwidth.