This paper presents an efficient reference impedance determination method, which is applicable to TLR calibrations performed on a wide variety of substrates, including those consisting of low resistivity material. The method is shown to be valid up to 40 GHz. It is based on the comparison of DC-resistance and scattering-parameter measurements of a resistor, a short and an open.
Gillon, R., Raskin, J.-P., Vanhoenacker-Janvier, D., & Colinge, J.-P. (1996). Determining the reference impedance of on-wafer TLR calibrations on lossy substrates. Proceedings of the 26th European Microwave Conference proceedings EuMC ’96, pp. 170-173. https://doi.org/10.1109/EUMA.1996.337545