High-Temperature RF Material Characterization Using a Dual-Chambered Rectangular Waveguide Fixture

A rectangular waveguide (RWG) fixture is proposed for the high-temperature RF characterization of materials. Composed of two RWGs in a side-by-side or over-under orientation, the new apparatus permits the calibration and specimen measurements to be collected simultaneously reducing high-temperature measurement time by two full days over the traditional method. In addition, the permittivity and permeability, determined from measured S-parameters, are independent of sample position and can be found in closed form. The design and construction of the dual-chambered RWG fixture are detailed. The closed-form, position-independent, permittivity and permeability extraction method is also discussed. Finally, high-temperature material characterization experiments are performed to validate the fixture. The errors in permittivity and permeability are estimated assuming uncertainties in sample thickness and measured S-parameters.