Convenient Waveguide Technique for Determining Permittivity and Permeability of Materials

Abstract

This article proposes a convenient technique for determining the permittivity and permeability of materials placed in a waveguide. Simplicity and repeatability of the method are achieved due to the utilization of contactless waveguide flanges and short-short-line (SSL) calibration technique. The grooves in the contactless flange prevent the electromagnetic field from leaking through the gap between the flanges even though misalignments exist. The SSL calibration uses a single line standard and two short standards. Since only one line standard is required, the test fixtures do not need to move during the calibration and measurement. With the help of contactless flanges and SSL calibration technique, the test fixtures could stay fixed in a plastic bracket. In addition, the line standard, the short standards, and the device under test (DUT) can be easily replaced without fastening screws. It is convenient when there are a large number of samples to be measured. The measured permittivity and permeability of polytetrafluoroethylene (PTFE) and carbonyl iron powders in the whole X-band showed the validity of the contactless flange and the accuracy of the SSL calibration technique.