Double-positive Metamaterials Research Articles

Characterization of Ni–Zn Ferrite Double-Positive Metamaterials for Pulsed Power Systems

A new type of metamaterial has been developed for the use in pulsed power systems. These materials have the applications in high-power microwave systems, dielectric-loaded components, and nonlinear transmission lines. We present a double-positive metamaterial created by incorporating several types of nickel–zinc ferrite powders into a silane binder. Measurements show these materials to possess positive relative permeability and permittivity values in the range of 3–6 for frequencies between 20 MHz and 2 GHz. The dielectric strengths of five different types of ferrite-based composites were measured to evaluate the potential of these materials for high-power applications. A pulse with a magnitude up to 100 kV and rise time on the order of tens of nanoseconds was used to determine the dielectric strength of disks with a diameter of 2.54 cm and a thickness of 0.2 cm. A maximum electric field of 163.79 kV/cm was sustained before breakdown. This paper presents a statistical analysis of the dielectric strength data and projects the power handling capabilities of the composites.

Experimental study of backscattering enhancement using acoustic double-positive metamaterials

Backscattering enhancement can be achieved by superscatterers which magnify the scattering cross section of an object. To realize this kind of scatterers, a posible approach on the conception of complementary media requires double-negative materials which may induce sound absorption. In this paper, a method for backscattering enhancement by using double-positive acoustic metamaterials is presented. A shell with discretely layered metamaterials is coated on the rigid cylinder to enhance the strength of backward scattering. Density and bulk modulus of the metamaterials are both positive and limited in a reasonable range. An experiment of backscattering enhancement is investigated. The layered shell is constructed from the metamaterials employing acoustic transmission line network. The scattering sound fields of the object and the layered structure with the same geometric scale are measured in a parallel plate waveguide. Scattering properties on both backward and forward direction are analyzed from the experimental results and the scattering enhancement effect with positive metamaterials is discussed.

Optical nanotransmission lines: synthesis of planar left-handed metamaterials in the infrared and visible regimes

Following our recent theoretical development of the concept of nano-inductors, nano-capacitors and nano-resistors at optical frequencies and the possibility of synthesizing more complex nano-scale circuits, here we theoretically investigate in detail the problem of optical nano-transmission-lines (NTL) that can be envisioned by properly joining together arrays of these basic nano-scale circuit elements. We show how, in the limit in which these basic circuit elements are closely packed together, the NTLs can be regarded as stacks of plasmonic and non-plasmonic planar slabs, which may be designed to effectively exhibit the properties of planar metamaterials with forward (right-handed) or backward (left-handed) operation. With the proper design, negative refraction and left-handed propagation are shown to be possible in these planar plasmonic guided-wave structures, providing possibilities for sub-wavelength focusing and imaging in planar optics, and laterally-confined waveguiding at IR and visible frequencies. The effective material parameters for such NTLs are derived, and the connection and analogy between these optical NTLs and the double-negative and double-positive metamaterials are also explored. Physical insights and justification for the results are also presented.