Design of a High-selectivity C-band Tunable Filter by Dielectric Movable Elements for SATCOM Applications

In this paper, the design of a mechanically tunable band-pass filter in waveguide technology operating in the C-band tunability range [4.4–5] GHz, for satellite communications (SATCOM), is presented. The resonance frequency tunability has been obtained by mechanically inserting movable dielectric cylinders within the waveguide filter. Impedance matching has been achieved by using two movable dielectric ridges, working as quarter-wave transformers. They have been placed at input and output filter ports and can move jointly with the dielectric tuning elements. Filter design has been carried out by adopting a suitable theoretical model, whereas the optimization has been achieved by numerical simulations. The proposed design approach provides key advantages in terms of simplicity, design effectiveness, and reproducibility, rendering it particularly suitable for industrial applications. A prototype of a high-selectivity tunable filter has been fabricated and characterized within the whole tunability range. The measurements show excellent agreement with simulated results.