If an incident plane wave of electromagnetic radiation hits a metallic grid of either type perpendicular to its path it will scatter, and the only propagating parts will be the zeroth order reflected wave and the zeroth order transmitted wave. The frequency of both of these electric fields will be equal, and the ratio of their amplitudes is Γ Γ ( ω ω ) , where Γ Γ is the reflection coefficient, and ω ω = g / λ λ is the normalized frequency. If we assume that the incident wave had unit amplitude, we can add the incident wave to the transmitted scattered wave to get the total amplitude of the transmitted wave, τ τ ( ω ω ) :