where it is assumed that both the incident electric field and incident magnetic field have been decomposed into two parallel and perpendicular polarizations and Γ<sub>||</sub> and Γ<sub>⊥</sub> denote the reflection coefficients at the interface between air and the impedance surface for the cases of parallel and perpendicular polarizations, respectively.These reflection coefficients are given by: Â :<math> R_{\|} = \frac{Z_0\cos\theta - Z_s} {Z_0\cos\theta + Z_s} </math>Â Â :<math> R_{\perp} = \frac{Z_s\cos\theta - Z_0} {Z_s\cos\theta + Z_0} </math>Â Â Â