Simple formula for the internal impedance of mixed carbon nanotube bundles

A simple formula for the internal impedance of mixed carbon nanotube (CNT) bundles is proposed in this paper. It can appropriately capture the skin effect as well as temperature effect of mixed CNT bundles. The computing time and results of the simple formula and the numerical calculation are compared with various mean diameters, standard deviations, and temperatures. It is shown that the proposed simple formula can improve the efficiency dramatically, and has very high accuracy in the whole frequency range considered, with maximum errors of 1.2% and 2.5% for the resistance and the internal inductance, respectively.