Figure 2

The configuration of the frequency-selective SPP structure, which is composed of three parts.

(a) The CPW section, in which w = 15 mm, g = 0.55 mm and H = 10 mm. (b) The transition with flaring ground and gradient grooves, in which h₁ = 0.5 mm, h₂ = 1 mm, h₃ = 1.5 mm, h₄ = 2 mm, h₅ = 2.5 mm, h₆ = 3 mm, h₇ = 3.5 mm and h₈ = 4 mm. The curvature of the flaring ground is k = 0.2. (c) The corrugated metallic strips, in which p = 5 mm, a = 3 mm, h = 4 mm and g₁ = 1 mm.