A stepped flange waveguide technique for determining tapered R-card sheet impedance

This paper introduces a reduced aperture flange waveguide technique capable of simultaneously measuring both reflection and transmission coefficients in order to characterize the tapered sheet impedance of a film in a nondestructive manner. This specialized technique employs a stepped flange waveguide and modal analysis approach in order to approximately treat the tapered film as a piecewise-homogeneous material. The main objective is to concentrate the incident electromagnetic energy into a smaller sample area of the tapered film clamped between two flanges. With the theoretical scattering parameters generated through the modal analysis, an iterative root search algorithm is utilized to extract the complex material parameters to achieve an effective sheet impedance profile for the tapered film. Experimental measurements are conducted with standard precision X-band (8.2 GHz to 12.4 GHz) waveguide components for validation, though the approach may be extended to additional frequency bands.