Microwave properties of low-loss polymers at cryogenic temperatures

Abstract

Dielectric loss tangent and permittivity of Polytetrafuoroethylene (Teflon), high density Polyethylene and cross-linked Polystyrene (Rexolite) were measured at temperature range from 28 K to 84 K and frequency of approximately 18 GHz. The material properties were determined by measurements of the resonant frequency and the Q-factor of a TE011 mode cylindrical superconducting cavity containing a sample under test. It has been demonstrated that these materials exhibit very low losses at cryogenic temperatures (2X10-6 for Teflon, 5x10-5 for HD Polyethylene and 1.1X10-4 for Rexolite). Due to low losses these materials can be useful in construction of various high Q-factor microwave devices for operation at cryogenic temperatures.