Reconfigurable Dual-Band Filtering Power Divider With Ultra-Wide Stopband Using Hybrid Microstrip/Square Defected Ground Structure

In this paper, a reconfigurable dual-band filtering power divider (FPD) with the wide tuning range and ultra-wide stopband is proposed. The hybrid stepped-impedance microstrip line/square defected ground structure (SIML/SDGS) can introduce a lowpass response with an ultra-wide stopband. Meanwhile, the coupled varactor-loaded tri-branch resonators with SDGS are utilized to adjust the coupling coefficient for improving passband bandwidth. To verify the aforementioned mechanisms, a reconfigurable dual-band bandpass FPD is developed with merits of the wide tuning range, high selectivity, and ultra-wide stopband. The measured results exhibit that the frequency tuning ranges of the proposed power divider are 57% and 41% for the dual-band, respectively. Meanwhile, the harmonic suppression is up to 23.5 times of the lowest passband center frequency (i.e., 0.85 GHz) with a rejection level higher than 25 dB.