A Ka-band planar TE011 mode cavity tunable filter using a mode-splitter ring

A TE011 Ka band tunable filter with a stable and continuous tuning performance is presented in this paper. A novel mode-splitter resonator and coupling configuration enabling cross-coupled planar TE011 filter realization is introduced in this work. The concept can be applied to back-to-back coupled TE011 resonator as well. The idea presented in this paper is verified through fabrication of a three-pole Ka-band tunable filter that demonstrates 500 MHz of tuning range with a stable RF tuning performance.