Determination of Spectral Focusing Features of a Metamaterial Slab

The realization of flat superlenses is a major application area of metamaterials. A slab of double negative (DNG) material is capable of imaging with a resolution below the diffraction limit. The focusing quality depends primarily on the amount by which the original spectrum of the source is restored behind the lens. Even a small deviation from the ideal case limits the spectrum of the transmitted field, which may result in a significant degradation of the focusing quality. In this work we determine the width of the transmitted spectrum as a function of the configuration parameters and establish a relation between the spectrum width and the imaging quality. Restrictions imposed on the focusing characteristics and difficulties arising in full wave simulations will be pointed out

Numerical analysis of focusing by a metamaterial lens

Over the last several years there has been a surge of interest in artificial materials because of their potential to expand the range of electromagnetic properties in materials. The so called metamaterials, also known as left-handed (LHM) or double-negative (DNG) materials with negative permittivity and permeability have attracted growing interest. An important application area is the realization of flat superlenses with imaging properties beyond that of conventional lenses. This work investigates the focusing properties of a lossless planar DNG slab with a relative permittivity and permeability both approaching the value -1. The relation between the imaging quality and the material parameters is examined both analytically and numerically. Results obtained from numerical simulations via the transmission line matrix method are compared to the analytical solution

Design of magnetic-resonant wireless power transfer links realized with two coils: Comparison of solutions

A novel approach for the rigorous design of magnetic resonant wireless power transfer links is introduced. We show how, starting from two coupled inductors and making use of general network theory, it is possible to derive analytic rules for designing the source and load terminations which provide the maximum power transfer efficiency or maximize the received power. We also show that, by adding suitable matching networks to two coupled inductors we can realize a wireless link acting as a 1:n transformer and having the all required tunable reactive elements on the primary side. The proposed topology greatly simplifies the design, since only an inductive coil and a fixed capacitance are required on the secondary side; in addition, when tuning is required due to coils misalignment or to link distance variation, it can be attained by acting on the transmitter side without the need for a feedback communication through the link. Moreover, when the load resistance is designed for maximum output power, its value is fixed and does not depend on the coupling. A numerical and experimental verification of the proposed approach is also presented