In this study, two independent methods to extract the constitutive parameters of large-scale (more than a wavelength long) metamaterial (MTM) structures are described. One method is based on fitting the simulated inner electric/magnetic field to the electric/magnetic field computed with an analytical model, whereas the other method is based on the scattering matrix parameters. The extraction methods are tested on three MTM structures [two single negative and one double negative (DNG)] and show results that are in good agreement. The extracted parameters were used to predict a focusing effect in a simulated spherical concave lens made of DNG MTM. The three MTM structures were experimentally measured for insertion loss in an anechoic chamber. For practical reasons, the experimental models were fabricated on Duroid substrates and scaled to operate in X-band. Detailed explanation of the construction of the MTMs and the anechoic chamber measurement setup is given. The transmission characteristics were measured at different frequencies and at different incident angles. The measured and simulated results are found to be in good agreement. In the DNG MTM, a peak transmission of -0.7 dB was measured, which to these authors' knowledge is the highest reported to date for such an MTM structure. Good transmission is maintained for incident angles of up to 45° from boresight.