Measurement and computation of thermally-induced currents in coaxial signal cables

Thermally induced current in low noise polymeric coaxial cables can introduce significant errors in certain applications. For e-beam crosslinked polymeric cable, the thermally induced current signal can be as high as 1 nA/m. The origin of such thermally induced signals is explained, based on the change of morphology and dielectric polarization as a function of temperature. The results of measurements carried out on three types of cables over a wide range of temperature are in good agreement with numerical simulations which involve the nonlinear thermal properties of the cable materials.