Abstract
Omega shaped metallization on a dielectric substrate if appropriately designed will exhibit plasmonic resonances when excited by microwaves. We present experimental results for the complex S‐parameters for four types of metamaterial slabs constructed with discrete omega shapes in a rectangular lattice. A double layer of omega shapes in a rectangular lattice is obtained by reflecting the pattern of one strip by +180° (Omega A), the third sample is realized by reflecting one strip by −180° (Omega B) and the fourth sample (Omega C) is realized by an alternate arrangement of the Omega A and Omega B samples in a rectangular lattice. The single layer sample is asymmetric (S11 ≠ S22), the two mirror image pair samples are perfectly symmetric with S11 = S22. Plasmonic resonances and band gaps were observed. The complex S‐parameters were used to extract the complex permittivity and permeability of the symmetric samples by inverting Fresnel formulae for the reflection and transmission coefficients of a planar slab normally illuminated by a plane wave. The data of the asymmetric sample was inverted with this procedure to obtain two sets of data, one set using S11 and S21 and another set using S22 and S12 for the extraction of complex parameters. A reflection operation on the Omega geometry by ±180° results in the switching of the electric and magnetic properties in certain frequency ranges. Band gaps have been observed for both Omega A and Omega B that coincide with short circuit regions for the real part of the impedance. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2624–2629, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21984