A Novel Independently-Tunable Dual-Mode SIW Resonator with a Reconfigurable Bandpass Filter Application

A novel, widely-tunable, substrate-integrated-waveguide (SIW), dual-mode resonator with mode-independent frequency tuning is presented. The first mode has a 94% tuning range, from 1.7–3.3 GHz with a measured quality factor (Q) from 150–400. The second mode can be tuned to be lower or larger than the first mode with better than 27% tuning range while maintaining a Q higher than 260 over the entire range. A second-order reconfigurable bandpass filter is designed utilizing a single dual-mode resonator. The filter is based on a doublet-configuration with a tunable center frequency from 2–3.2 GHz and a controllable finite transmission-zero that can be located on either the upper or the lower side of the passband. The filter has an insertion loss better than 1.1 dB over the entire tuning range.