Varactor-Loaded Continuously Tunable SIW Resonator for Reconfigurable Filter Design

This paper presents a novel concept of low-loss tunable resonator based on a combline SIW cavity loaded with GaAs varactor tuning diodes. The center frequency of the resonator can be continuously tuned between 2.6 -3.1 GHz. The device has been fabricated on a conventional two-layer PCB process using a low-cost standard high-frequency laminate (i.e. epsilon(r) = 3.55, tan delta = 0.003). The measured tunable Q ranges from 40 to 160 over the whole tuning range. The proposed tunability concept could be of great interest for the design of high-Q planar reconfigurable filters.