A novel dual-band filter power divider (DB-FPD) with controllable transmission zeros (TZs) is designed using a slotline multimode resonator (SLMR) in this letter. Using the stub loading technology, each resonator mode of the SLMR can be easily controlled. Accordingly, a dual-band bandpass filter is realized. Four TZs are generated due to the loaded stubs on the SLMR and feeding network, which can improve the out-of-band selectivity. Finally, without introducing additional circuits, a DB-FPD with good performance is realized. For verification, a prototype operating at 2.01 and 4.79 GHz is fabricated and measured. The measured results are basically consistent with simulated ones. The 3-dB fractional bandwidths are 29.7% (1.72~2.32 GHz) and 7.99% (4.58~4.96 GHz), respectively, and the isolation in each band is better than 14 dB.
A novel high-selectivity bandpass filter based on a defected ground structure and substrate integrated coaxial line is proposed. Three transmission zeros near the passband are achieved by introducing a divergent-shaped resonator and two spindle-shaped defected ground structures, resulting in a high selectivity. To verify the proposed structure, one prototype with a center frequency of 4.94 GHz is designed and fabricated. The measured results show that three transmission zeros respectively located at 3.92, 4.36, and 6.00 GHz are obtained. The 3-dB passband bandwidth is 14.2% from 4.59 to 5.29 GHz. The upper stopband rejection is better than 20 dB from 5.71 to 11.31 GHz.