$Ka$-Band Miniaturized Quasi-Planar High-$Q$ Resonators

Air-filled copper Ka-band resonators with heights between 250-700 mum are demonstrated with measured unloaded Q factors between 440-829. The low-profile quasi-planar resonators are fabricated using a sequential metal deposition process. Miniaturization of up to 70% with respect to a TE₁₀₁ quasi-planar resonator is accomplished by reducing the footprint of the resonator while maintaining the height. Finite-element simulations predict the measured resonant frequency within less than 1%. Due to fabrication imperfections, Q _un is measured to be approximately 15% less than predicted. The resonators are compatible with air-filled rectangular microcoaxial feed lines fabricated in the same metal-deposition process.