A two-dimensional negative refractive index material is proposed. The material has a bulky structure composed of dielectric prism cells with metal patterns. The material is expressed by an equivalent circuit. The propagation regions of two left-handed modes calculated from the equivalent circuit exist near the propagation regions obtained by electromagnetic simulation. It is confirmed by simulation that the incident plane wave goes into the material with low reflection by using the second left-handed mode and attaching metal conversion strips around the material. A negative refractive index slab lens with 15×9 cells is made to measure the field distribution of wave out of the lens. It is shown that the resolution of the slab lens exceeds the diffraction-limit.

A left-handed material with simple structure is proposed. The material is composed of periodic metal strips exhibiting both electric property and magnetic property. The dispersion relations and the transmission characteristics are confirmed experimentally. The main field pattern of guided mode in the material is similar to that of the plane wave, and a transmission characteristic with low reflection is obtained for an impedance matching region.

The left-handed (LH) operation of a three-dimensional (3-D) LH material composed of wired metallic spheres is experimentally confirmed. A 15153-cell periodic structure designed to have an isotropic LH characteristics is fabricated by a 3-D printer with post plating technology, and near-field measurements of refracted waves by the negative refractive index slab lens are carried out. The dispersion characteristics measured from the near-field distributions on the surface of the LH material clearly show that the structure supports the backward waves at 12 GHz band. It is also shown experimentally that the resolution of the slab lens exceeds the diffraction limit by near field measurements with a single source and adjacent two sources. In addition, near-field measurements from the LH material near the Γ-point frequency at 12.90 GHz are carried out. A highly directive plane wave with a single point source is observed and the near-zero-index operation has been confirmed.

A novel planar composite right/left handed (CRLH) transmission line (TL) with double-sided metal patterns, which is advantageous in high scalability and low-cost fabrication, is proposed. Fundamental characteristics of the unbalanced and balanced CRLH TLs are confirmed numerically and theoretically both by full-wave finite-element method (FEM) simulations and the equivalent circuit analysis in terms of dispersion characteristics and characteristic impedances for the periodic structure. It is also shown that the relations between the left-handed circuit parameters and the geometrical parameters of the unit cell are simple and intuitive, which is useful for designing the CRLH TL. Experiments on 10-cell unbalanced and balanced CRLH TLs are carried out and the left-handed and right-handed wave propagations are confirmed by scattering parameter and near field measurements.

A novel purely distributed two-dimensional (2D) planar structure with a negative refractive index (NRI) is proposed. The structure consists of a 2D periodic array of unit cells with metal patterns on the both sides of a substrate. The unit cell with the dimension of 55 mm2 is designed at an operation frequency of about 5 GHz by full-wave finite element method simulations. Numerical simulations on the dispersion characteristics are carried out and NRI property of the structure is confirmed. A equivalent circuit taking into account the mutual capacitance between the adjacent ports in the unit cell is introduced, and theoretical investigations based on the equivalent circuit reveals that the anisotropy can be controlled by the mutual capacitance. A 1020 unit-cell NRI material is fabricated and the NRI property has been confirmed experimentally in excellent agreement with Snell's law.

A compact, nonradiative, and easy fabricated left-handed material composed of planar circuit-type resonators in a cutoff waveguide is proposed. It is shown that the TE-type evanescent field is equivalent to the field in ε-negative material and the resonator works as a particle with negative permeability. The existence of a left-handed mode is ensured by a field distribution and a dispersion relation. After showing that the two constituents have an influence on the permittivity or the permeability of the material, on the basis of an idea of impedance, the material is matched to a conventional waveguide. Finally the material can be applied to a left-handed leaky-wave antenna.