VO2 Switch-Based Tunable 3-D Cavity Filters

This article presents the design and implementation of vanadium oxide (VO₂) switch-based tunable 3-D cavity filters. The proposed concept employs switched strip lines integrated with cavity resonators to tune their resonance frequencies. This eliminates the need to use variable/switched capacitors, which are known to degrade the loaded Q of the filters over the tuning range. Combline filters and dielectric filters integrated with VO₂ switches are designed, fabricated, and measured. The measurement results verify the tunability and feasibility of using the proposed tuning scheme to realize a relatively high-Q VO₂ combline and dielectric resonator tunable filters that can maintain their Q values over the tuning range.