Broadband radio frequency conductivity measurement technique for engineered composites

In this study, the authors present a broadband conductivity measurement technique suitable for highly conductive engineered composites. The proposed technique is based on reflection measurement using an open-ended coaxial probe. To improve measurement accuracy over a broad bandwidth (200:1, 100 MHz-20 GHz), the authors implement a broadband probe calibration process to eliminate frequency-dependent error terms caused by probe aperture radiation and higher-order mode excitations. The validity of the proposed technique is demonstrated by conductivity measurements for several engineered composites, such as metallo-dielectric stack, a carbon nanotube composite and a conductive fibre.