Varactor-loaded continuously tunable SIW resonator for reconfigurable filter design

Abstract

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<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</inf>=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.