Determination of the electrical conductivity of carbon/carbon at high microwave frequencies

We present an accurate measurement of the electrical conductivity of carbon/carbon (C/C) composites in higher range of microwave frequencies. The composite is an 8 mm thick C/C laminate 2D woven fabric, machined to create a rectangular waveguide. Transmission and reflection parameters are acquired within a broad frequency band, ranging from 23 to 30 GHz, and used for the evaluation of the power loss in the waveguide and to extract the C/C electrical conductivity. The obtained conductivity values at microwave frequencies are about 10 times lower than those measured at very low frequencies. The effects of temperature are also investigated, and the variation of the conductivity with the temperature is reported.