This paper presents a compact varactor-tuned dual-band bandpass filter with independently tunable passbands and high selectivity. The filter consists of two varactor-loaded half-wavelength dual mode resonators, each of which features independent tunability of odd- and even-mode resonant frequencies by varying the capacitances of the corresponding loading varactor diodes. Benefiting from this feature, the filter offers two independently controllable passbands. In addition, hook-shape feed lines are utilized to create transmission zeros between the two passbands, which enhances the selectivity of the filter.
