Microwave Measurements of High-Loss Liquids with Transmission Line and Resonant Methods

The paper presents a comparison between transmission/reflection (T/R) and resonant methods employed for the characterization of complex permittivity of high-loss liquid The liquid under test is $\mathbf{5 0 \%}$ aqueous solution of propan-2-ol The T/R method with a meniscus-removal algorithm utilizes a 7 mm coaxial line in a semi-open test cell configuration and the complex permittivity is measured in $0.2-18 \mathrm{GHz}$ bandwidth. For the resonant method, a dielectric resonator cavity operating in $\mathrm{TE}_{01 \delta}$ mode at a nominal frequency of $2.45 \mathbf{~ G H z}$ is utilized For both methods, the dielectric constant and loss tangent of the $50 \%$ aqueous solution of propan- 2 -ol are extracted revealing good agreement of the obtained results and confirming their applicability for the characterization of high-loss liquid materials.