Tunable Dual-Band Coaxial Filter With Independent Band Control Using a Single Tuning Element Per Band

This paper presents a tunable dual-band filter featuring a single tuning element for each band. A shaped cavity generates distinct capacitive loading for the resonators as they rotate within the cavity. Each resonator is aligned and pinned to a metallic rod for rotation. The design enables independent control of each band, allowing the passbands to be tuned either simultaneously or independently. Additionally, the number of tuning elements remains unchanged when designing higher-order filters, offering a scalable and efficient design.