High accuracy broadband measurement of anisotropic dielectric constant using a shielded planar dual mode resonator

We investigate a proposed shielded dual mode planar ¿RA¿ resonator used for measuring the uniaxial anisotropic dielectric constants of planar substrates. Prior microstrip RA resonators have been unshielded, which introduces error due to radiation, especially for thick substrates. A detailed error evaluation is performed and presented. The resonator is long, allowing evaluation of nearly 100 resonances. Each pair of resonances of the dual mode resonator is evaluated to determine two substrate dielectric constants, one for horizontal (parallel to the substrate surface) electric field and the other for vertical electric field. Broad band anisotropic dielectric constants extracted from resonator measurements from 0.2 to 10 GHz are presented.