A High-Power Low-Loss Continuously Tunable Bandpass Filter With Transversely Biased Ferrite-Loaded Coaxial Resonators

Tunable Coaxial Bandpass Filters Based on Inset Resonators

“…Considering the drawbacks of the aforementioned technologies, loaded-waveguide structures have attracted more attention in tunable filters applications due to being much more compact when compared with hollow waveguide designs, while still providing comparably high quality factors. Accordingly, various loaded-waveguide tunable filter designs were presented based on dielectric resonators, conventional metallic half-wavelength, and combline configurations using different mechanical tuning means [5]- [20]. A 2.5 GHz tunable λ/2 coaxial filter was presented in [5] with a 20% tuning range by using a common element which rotates all of the resonators simultaneously inside an elliptical cavity, providing a means of tuning the operation frequency.…”

“…According to the authors' knowledge, this is the only tunable filter available in the literature based on the conventional λ/2 resonators. On the other hand, several combline-based tunable filters were presented using different tuning elements and means [6]- [13], [18]- [20]. A straightforward approach is by using mechanically, vertically movable tuning screws, disks, or sidewalls in the vicinity between the combline resonators and the top part of the metallic cavity [6]- [10].…”

“…Unfortunately, they also experience noticeable deterioration in the Q u with the tuning process. Besides the above mechanical-based tuning technique which is the most favorable, couple of loadedwaveguide filters were introduced using electrical and magnetic tuning elements to attribute fast tuning speed [18]- [20].…”

“…Similarly in [19], 30% varactor-tuned combline filters were implemented with a quality factor of 173 to 418. Also, a two-pole L-band ferrite-loaded tunable combline filter was introduced in [20] with 41% tunability and a Q u varies from 1223 to 2425. It can be shortly said that both electrical and magnetic tuning means still need more development to be employed effectively in tunable waveguide filters and compete with the mechanical-based tuning techniques.…”

Desenvolvimento de um filtro passa-baixa de alta potência supressor de harmônicos baseado na tecnologia de substrato suspenso

“…Em [10], é apresentado um filtro passa-faixa de ressoadores acoplados em banda L com banda de rejeição livre de espúrios até o quinto harmônico e capacidade de potência de pico de 250 W com 25% de ciclo de trabalho. Em [11], é apresentado um filtro de ressoadores acoplados por indutância mútua com capacidade de potência média de 129 W (800 W pico), com banda de rejeição limitada ao segundo harmônico. Em [12], dois protótipos são apresentados, usando ressoadores coaxiais e ressoadores em linhas em fita acoplados por circuitos concentrados passa-baixa, com capacidade de potência média de 100 W e 2 kW de pico em banda L com banda de rejeição até o quinto harmônico.…”