Experimental and numerical investigations of oscillations in extracted material parameters for finite Bragg stacks using the NRW method

A 1D dielectric finite Bragg stack situated in a rectangular waveguide and illuminated by the fundamental TE₁₀ mode is examined analytically, numerically, and experimentally. Calculated as well as measured scattering parameters are used to extract the effective/equivalent material parameters for three specific configurations of its constituent unit cell. Particular attention is devoted to the absence/presence of certain oscillations in the extracted material parameters, depending on the unit cell configuration. The results for the finite Bragg stack are further verified to agree with those of an infinite Bragg stack, for which the dispersion equation is used in conjunction with the Floquet-Bloch harmonics expansion to extract the material parameters. It is shown that the extracted material parameters for the finite and infinite Bragg stacks agree for the symmetric unit cell configuration.