Analysis of a Variable SIW Resonator Enabled by Dielectric Material Perturbations and Applications

This paper details the analysis of a variable substrate integrated waveguide resonator enabled by dielectric material perturbations. A circuit model and closed-form expressions are developed. Fluidic dispersions composed of low dielectric oil and high dielectric particles are utilized in a prototype resonator to provide proof-of-concept demonstrations for three applications, which are: 1) a tunable resonator; 2) a material measurement device; and 3) a fluid sensor. Theoretical values for the dielectric constant and loss tangent of the fluidic dispersion show a possible tuning range of ~ 20% across X-band. However, measurements show the materials composing the fluidic dispersion have more losses than expected and hinder performance for practical filtering applications (Q drops to 10 s). It is noted that utilizing better materials for the fluidic dispersions will greatly increase the performance as a tunable resonator. In the next application, the measurements on the prototype resonator and parametric studies from simulation are used to estimate new properties for the fluidic dispersions constituents. The final application utilizes the prototype as a fluidic sensor for measuring the volume fraction of a particulate in a fluid medium.