Grzegorz Lubkowski

Effective Modeling of Double Negative Metamaterial Macrostructures

This paper presents a numerical procedure applied to the modeling of double negative metamaterial (MTM) structures. At the unit-cell level, the properties of the MTM are described by the extracted isotropic constitutive parameters, dispersion diagrams, and higher order modes analysis. The information gathered at the unit-cell level is used to characterize and homogenize the MTM macrostructure. By comparison of the simulation results for the effective and detailed macrostructures models, the applicability of this approach is confirmed and the significant savings of numerical costs are pointed out.

Analysis of Single-Cell Modeling of Periodic Metamaterial Structures

We propose a comparison of two approaches to analyze the periodic arrays of left-handed metamaterials by field simulations in a single unit cell. First, a scattering matrix analysis in time domain is able to produce broadband results. The set of transfer functions between a small number of input and output ports of the unit cell is able to describe its macroscopic behavior, where, however, the appearance of higher order modes is systematically neglected. As a reference result with respect to this issue, an eigenvalue analysis with periodic boundary conditions provides one point of the dispersion relation of the array per simulation run. We show how these results can be transformed into each other, and present a quantitative analysis of the impact of higher order modes on the effective array properties.

Waveguide Miniaturization using Spiral Resonators and Dipole Arrays

The novel idea of waveguide miniaturization presented in this work relies on the insertion of spiral resonators and dipole arrays in the symmetry plane of the waveguide. Waveguide miniaturization in this context means moving the first transmission band of a waveguide below its cutoff frequency. The design, fabrication and measurement of miniaturized rectangular waveguides are described in this paper. The experimental results are compared with the simulations validating the proposed design approach. Obtained results are referred to the solutions known from the literature

Experimental Study of Subwavelength Waveguides Loaded by Electric and Magnetic Resonant Scatterer Arrays

The novel idea of the subwavelength waveguide transmission presented in this work relies on the insertion of electric and magnetic scatterer arrays in a rectangular waveguide. The transmission below waveguide cutoff takes place in the form of forward or backward waves, depending on the type and orientation of the inserted resonant elements. The design, fabrication and measurement of the loaded waveguides is described in this paper. The experimental results are compared with the numerical simulations and referred to the theoretical proposals known from the literature.

3D Field Simulations using FI Time Domain Technique of Wedge-and Parabolic-Shaped Left Handed Materials (LHM)

Wedge- and parabolic shaped structures composed of split-ring resonators (SRR) and wires are numerically simulated by evaluating its refraction and radiation behaviour using CST MICROWAVE STUDIOregs finite integration time domain solver. Negative phase velocity inside these metamaterials is demonstrated in the left-handed band and the Snells Law is conformed in terms of its refraction behaviour. Effective electric permittivity and magnetic permeability for these metamaterials are extracted directly from S-parameters of a SRR unit cell described with Lorentz/Drude dispersion models. It is demonstrated that both, models composed of a homogeneous left-handed-material (LHM) and models consisting of a large number of microscopic unit-cells show similar results. Antennas designed with metamaterials offer the ability to adjust phase center easily thereby showing a larger constant phase angle

Metamaterial Loaded Waveguides for Miniaturized Filter Applications

The metamaterial loaded waveguides offer the possibility to obtain desired transmission characteristics below the cutoff frequency of the hollow waveguide. This property allows for the design and fabrication of narrowband and broadband miniaturized waveguide filters. The metamaterial inclusions are designed with CAD tools and fabricated in the form of resonant elements arrays loading the X-band rectangular waveguide. The experimental results are compared with the simulations validating the proposed design approach. Index Terms – Metamaterials, Waveguide Filters