A zirconia cylindrical TM010 cavity for permittivity measurements at 1 GHz

Abstract

The most accurate dielectric measurements are made by resonant cavity methods, the circular TM010 type being the simplest and most common. However, an airfilled such cavity at 1 GHz needs to be 250 mm in diameter. There is another problem as well: its limited applicability with very lossy samples, due to a too low Q value. This paper describes the development and properties of a metalized zirconia ceramic cavity for use at about 1 GHz. With its permittivity $\varepsilon'=30$ its diameter becomes 40 mm instead of 150 mm for the airfilled version. Additionally and importantly, the dynamic range of the loss factor $\varepsilon''$ is greatly expanded. The calibration procedure using numerical retro- modelling is described and a measurement example of a ternary alcohol mixture is carried out. The accuracy is also estimated