Date of Award
Master of Science in Electrical Engineering
Department of Electrical and Computer Engineering
Michael J. Havrilla, PhD.
Measurement of the electromagnetic properties of materials at high temperatures is important for industrial, scientific, medical, and aerospace applications . Current high-temperature electromagnetic material characterization is a time consuming process that typically requires three days to collect data from one material specimen. For example, the standard high-temperature process involving rectangular waveguides  requires measurements of the sample (1), the empty waveguide (2), and a metal short standard (3) completed in separate heated runs over three days to perform the Nicolson-Ross-Weir inversion algorithm for computing permittivity and permeability. The technique developed here will reduce the high-temperature measurement process from three days down to just one day. The research uses a position independent approach for isotropic materials that averages forward and reverse traveling waves for effective transmission and reflection parameters. It is shown that this averaging effect eliminates the need for a metal short measurement, thus reducing high-temperature measurement time by one day. In addition, a new dual chambered waveguide de- sign will help reduce measurement time down to just one day. This is accomplished through simultaneous measurement of the inserted sample in one of the chambers and the empty waveguide of the second chamber. A vector network analyzer (VNA) will be used to run X-band data collects at incrementally increasing temperatures up to approximately 1000◦ F. The results will be the test material’s permittivity and permeability as calculated from VNA measured S-parameters at increasing temperatures. These results will be compared with other known techniques in order to validate the new high-temperature process.
DTIC Accession Number
Sovern, Jeffrey S., "Electromagnetic Characterization of Materials Using a Dual Chambered High Temperature Waveguide" (2016). Theses and Dissertations. 322.