Polyethylene teraphthalate (PET). Multiple reflections due to substrate-air interface and horn antenna(s) were eliminated using a time gated Fourier transformed pulse excitation. The graphene film on PET substrate increased the reflection (S 11 ) by 3-4dB over the entire frequency range, and the transmission coefficient (S 21 ) decreased by 1-2dB. The surface conductivity σ g ≈ 0.003-0.005 S/sq. was calculated from measured scattering parameters using Liang's formula. The result was comparable to its theoretically predicted values (Kubo's formula) over the frequency band of interest.