Microwave dielectric properties degradation of ceramic-polymer composites by electron irradiation

Composite materials with permittivities of the order of 10 and dielectric losses less than 0.001 are being developed as high-frequency substrates for telecommunication applications. Composites fabricated with a zirconium tin titanate ceramic filler dispersed inside of a thermoset epoxy-based polymer matrix have been studied at 12 GHz as a function of temperature (from 100 K to 473 K) and during electron irradiation on a 2-MeV Van der Graaff electron accelerator up to a total dose of 40 MGy. The results show a dielectric loss increase and permittivity decrease with increasing temperature, and a radiation induced dielectric degradation due to polymer structural changes.