Whispering gallery modes in rutile resonators at millimeter wave frequencies

Whispering gallery modes in single crystal rutile resonator were measured at frequency range 15-30 GHz. Predicted and measured values of resonant frequencies for several WGM were in excellent agreement. Permittivity components parallel and perpendicular to anisotropy axis have been evaluated and their values were epsilon (perpendicular to)=85.8 +/-0.2% and epsilon (\ \)=163.2 +/-0.2% at room temperature and frequencies 15-30 GHz. Dielectric loss tangent components of rutile measured at room temperature and frequency of 25 GHz; were tan delta (perpendicular to) =4.2x10(-4)+/- 10% and tan delta (\ \)=5.7x10(-4)+/- 10%.