Three-dimensional isotropic perfect lens based on LC-loaded transmission lines

An isotropic three-dimentional perfect lens based on cubic meshes of interconnected transmission lines and bulk loads is proposed. The lens is formed by a slab of a loaded mesh placed in between two similar unloaded meshes. The dispersion equations and the characteristic impedances of the eigenwaves in the meshes are derived analytically, with an emphasis on generality. This allows designing of transmission-line meshes with desired dispersion properties. The required backward-wave mode of operation in the lens is realized with simple inductive and capacitive loads. An analytical expression for the transmission through the lens is derived and the amplification of evanescent waves is demonstrated. Factors that influence enhancement of evanescent waves in the lens are studied and the corresponding design criteria are established. A possible realization of the structure is outlined.Comment: 22 pages, 15 figure

Experimental verification of the key properties of a three-dimensional isotropic transmission line based superlens

Design and experimental realization of a three-dimensional superlens based on LC-loaded transmission lines are presented. Commercially available components and materials are used in the design. Transmission properties of the designed structure are studied experimentally and the observed lens properties are compared with analytical predictions. Backward-wave propagation and amplification of evanescent waves in the prototype structure are verified both analytically and experimentally.Comment: 12 pages, 10 figure

On Artificial Magneto-Dielectric Loading for Improving the Impedance Bandwidth Properties of Microstrip Antennas

In the present paper we discuss the effect of artificial magneto-dielectric substrates on the impedance bandwidth properties of microstrip antennas. The results found in the literature for antenna miniaturization using magnetic or magneto-dielectric substrates are revised, and discussion is addressed to the practically realizable artificial magnetic media operating in the microwave regime. Using a transmission-line model we, first, reproduce the known results for antenna miniaturization with non-dispersive material fillings. Next, a realistic dispersive behavior of a practically realizable artificial substrate is embedded into the model, and we show that frequency dispersion of the substrate plays a very important role in the impedance bandwidth characteristics of the loaded antenna. The impedance bandwidths of reduced size patch antennas loaded with dispersive magneto-dielectric substrates and high-permittivity substrates are compared. It is shown that unlike substrates with dispersion-free permeability, practically realizable artificial substrates with dispersive magnetic permeability are not advantageous in antenna miniaturization. This conclusion is experimentally validated.Comment: 22 pages, 14 figures, 5 tables, submitted to IEEE Trans. Antennas Propaga

Near-field enhancement and imaging in double cylindrical polariton-resonant structures: Enlarging perfect lens

We experimentally demonstrate a prototype of a cylindrical enlarging lens capable of enhancing and restoring evanescent fields. The enabling phenomenon is the resonant excitation of coupled surface modes in a system of two cylindrical arrays of small resonant particles. As was shown in [J. Appl. Phys. 96, 1293 (2004)], this phenomenon in planar arrays can be used in electromagnetic near-field imaging. Here, we use a similar structure in a cylindrically symmetric configuration, which gives us a possibility to obtain an enlarged near-field image.Comment: 7 pages, 4 figure

Experimental demonstration of sub-wavelength image channeling using capacitively loaded wire medium

In this letter we experimentally demonstrate a possibility to achieve significant sub-wavelength resolution of a near-field image channeled through a layer of an electromagnetic crystal. An image having radius of $\lambda/10$ has been realized using an electrically dense lattice of capacitively loaded wires. The loading allows to reduce the lattice period dramatically so that it is only a small fraction of the free-space wavelength. It is shown that losses in the structure only decrease the total amplitude of the image, but do not influence the resolution.Comment: 4 pages, 7 figures, submitted to PR