We have constructed a novel microwave frequency resonator that can sit within the GEM and POLARIS diffractometers and will allow us to simultaneously collect diffraction and dielectric data for sample materials. The resonator consists of machined aluminium with a thinned 2cm window to minimise its scattering. The resonator sits around a quartz tube with an internal gas permeable frit on which sits our samples. The quartz tube is connected to a custom designed gas panel which allows us to flow gas over our sample during data collection, with the exhaust gas fed into a mass flow meter and quadropole mass spectrometer. In this way we may measure dielectric and diffraction data as a function of composition and time and thus correlate changes in dielectric properties with concomitant changes in structure.