Ka-band transmission measurements of dielectric coplanar plates at high temperatures using solar energy

If one is looking for dielectric properties of natural or synthetic materials, it is easy to find lots of references and tables, most of them even covering a broad bandwidth of frequencies. Unfortunately these values are only valid at room temperature, and the dielectric properties are not generally supposed to stay constant with temperature. In order to measure dielectric properties at high temperatures, a new method has been developed and tested for the first time. The material can be heated at the same time as measuring the transmission coefficient by electromagnetic wave propagation (in K.-band) through the medium, without having to remove the sample from the measurement setup. The Solar Furnace at the German Aerospace Center (DLR) in Koln-Porz made this possible, using concentrated solar radiation to heat the sample non-invasively.