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. ε
_r
=3.55, tanδ=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.