Free-Space Material Measurement for a Small Dielectric Plate at W-band

A free-space material measurement for a small dielectric plate using a truncated Gaussian beam whose beam width is smaller than the material under test (MUT) is described. Measurement results of two glass plates of different thicknesses at W-band (75–110 GHz) show its validity and the minimum beam width of the truncated Gaussian beam for the reliable material property measurement of a small planar MUT.