Advances in Mechanically Tuned Coaxial and Dielectric Loaded Waveguide Filters

This article overviews the topic of reconfigurable RF filters and focuses on some of the advances in mechanically tunable coaxial and dielectric resonator filters, especially over the past two decades. In the first part of the paper, we summarize the various tunable filter classes and emerging tuning techniques, beside discussing the key design characteristics of tunable RF filters. Then, the article dives into several of the recent advanced tunable coaxial and dielectric resonator filter designs operating particularly below 10 GHz and featuring highly desirable advantages including the miniaturized size, high quality factor, stable performance, and wide tuning ranges. Finally, we conclude with the different challenges and possible future directions of research and development for reconfigurable RF filters based on coaxial and dielectric resonators.