Complex permittivity measurements of extremely low loss dielectric materials using whispering gallery modes

Whispering-gallery modes are used for very accurate complex permittivity measurements of both isotropic and uniaxially anisotropic dielectric materials. A mode-matching technique is used to find the relationship between the complex permittivity, resonant frequency, and the dimensions of a resonant structure. The total uncertainty in permittivity is smaller than 0.05 percent and is limited principally by uncertainty in sample dimensions.