The dielectric constant and thermal expansion of the ceramic-filled plastic RT Duroid at low temperatures

摘要

A widely used substrate material for microstrip circuitry is the plastic polytetraflouroethylene (PTFE) which contains ceramic or glass-particle filling in order to provide a range of dielectric constants. However, there is little or no information available on the low-temperature properties of such a material. Such information is of considerable interest with the recent advent and increasing application of high-T_C superconductors (HTS) at microwave frequencies.