Executive Summary : | Microwaves can penetrate dielectric materials, allowing for accurate measurements of properties like dielectric constant and loss tangent. The cavity perturbation technique is considered the most accurate method for measuring electromagnetic properties of materials. By introducing a known volume of the material into a high-quality factor resonator, the dielectric constant and loss tangent can be accurately measured. Traditional measurements are performed using vector network analyzers and conventional waveguide cavities. Automation efforts for deployable sensors employ complex readout circuits. Recent studies have improved the analysis of resonance characteristics and quality factors for various cavity geometries, designed klystron cavities, high-sensitivity displacement sensors, and high-resolution accelerometers using differential mode cavities. The group has collaborated with materials scientists to evaluate microwave properties of nanomaterials for novel shielding and absorbing materials. The proposal aims to extensively study re-entrant cavities and develop several RF-based sensors using them. The profile of the cavity, post, and re-entrant gap impacts its overall electromagnetic characteristics. Accurate evaluation of EM properties requires introducing a small volume of the material under test. The design and analysis of robust high-Q cavities, least sensitive to fabrication tolerance, and self-compensated cavities for high or low temperatures are desirable. Several variants will be developed as a platform technology for low-cost sensors for various applications. |