Changes

The '''Dispersion Sweep '''option of the Simulation Mode dropdown list performs a sweep of constant k_l wavenumber values. This is a specialized sweep for the constant transverse wavenumber method that EM.Cube's [[FDTD Module]] uses to model periodic structures illuminated by a plane wave source. The real advantage of a dispersion sweep is that through a one-dimensional sweep of k_li, you can find the reflection and transmission coefficients for all combinations of frequency f_j and incident angle θ_j such that (2π/c) . f_j. sin θ_j = k_li. This provides a complete picture of the dispersion behavior of your periodic structure. The sweep data can be graphed as a wavenumber-frequency intensity plot (also known as beta-k diagram) that projects the eigenvalues of the periodic structure. The horizontal axis represents the constant transverse wavenumber k_l (or beta). The vertical axis represents frequency. Sometimes, the free space wave number k₀ = (2π/c).f is used as the vertical axis, hence, the term beta-k diagram. However, EM.Cube plots frequency vs. wavenumber. Both the horizontal and vertical axes start from 0 and extend to f_max and k_l,max, respectively, where f_max = f₀ + Δf/2, and Δf is the specified bandwidth of the project. For this sweep option you have to specify the number of wavenumber samples. Note that the dispersion sweep is run for a fixed given value of the plane wave incident angle f φ as specified in [[FDTD Module]]'s Plane Wave Dialog.