Low-Loss Materials over 2 mm Thick with Fabry-Perot Resonator (25 - 110 GHz)

Measurement Results

Key Point!

• Low-loss materials can be measured even with samples thicker than 2 mm.
• The resonance shift is determined by sample thickness and dielectric constant. If dielectric loss tangent is small, even thick samples can be measured.

Fabry-Perot resonators are ideal for evaluating thin, low-loss materials. In a Fabry-Perot resonator, dielectric constant is calculated from the resonance shift before and after inserting the material, and the amount of shift is determined by the material dielectric constant and thickness. If the material has a small dielectric loss tangent, even somewhat thick samples can be measured. In this example, PTFE thicker than 2 mm and polyethylene thicker than 3 mm were evaluated. Clean frequency characteristics were obtained over a wide range from 25 to 110 GHz. However, depending on the resonance shift, some frequency points may not be measurable; results at those points are omitted.