Identification of the complex relative dielectric constant of porous polymers at different degrees of humidity

In order to investigate the complex relative dielectric constant of different materials over a frequency range of 50MHz to 3 GHz a setup has been built that allows rfmeasurements in a climate chamber. Within this chamber the temperature and humidity can be changed and be measured by accurate sensors. The construction of the rf-part of the setup has been made with an outer cylindrical shell that allows climate interactions through its large orifices. Methods for calculating the complex relative dielectric constant from the measured scattering parameters are presented and the changes of the relative constants due to different humidity conditions are shown. © Author(s) 2008