The dielectric characterization of dielectric material at
microwave frequencies is a challenging problem. In this paper the complex permittivity of MgTe2O5 dielectric material has been measured as a function temperature and frequency employing few higher order quasi TEOnp modes excited in a disc shape sample. The loss tangent varies between 2.lxl0-4 and 4.5xl0 in the frequency range 9 GHz and 25 GHz and 1.lxl0 and 4.3xl0 in the temperature range 15 K and 295 K. Measured samples of MgTe20s exhibited exceptionally high and reversible dependence of the dielectric losses on the humidity and can be used as
humidity sensors.