B. Near-field Measurements We scanned an area of 150 mm x 50 mm at a distance of 1 mm above a planar circuit with a CPW, a radial balun and a Vivaldi antenna. The CPW and the radial balun were fabricated with a 20-m-thick Cu film on a 0.8-mm-thick glass-epoxy wafer. The planar circuit was attached to the adapter transiting the CPW from a coaxial cable to which the sine-wave signal was supplied at 8 GHz. For comparison, a commercially available electromagnetic simulator (MW-Studio/ CST GmbH) calculated the electric field with the model. The measured and calculated near-field intensity distributions are shown in Figs. 5.