Compact 4.0–5.1 GHz Filtering Power Divider With Low Insertion Loss and Wide Stopband Using RC-Loaded Coupled SIDGS Resonators

In this paper, a filtering power divider (FPD) with low insertion loss and wide stopband is proposed based on the RC-loaded coupled substrate-integrated defected ground structure (SIDGS) resonators. Such coupled resonators can not only realize the integration of filtering and power division, but also introduce wide stopband by mutual suppression. Moreover, good isolation around passband is obtained by directly loading resistors and capacitors on the coupled resonators. Besides, spur-lines embedded in the microstrip feed-lines are used to further suppress the harmonics. To verify the mechanisms mentioned above, a prototype FPD operating at 4.50 GHz (i.e., f
0
) with 0.8 dB insertion loss is implemented and fabricated. The measured in-band isolation is better than 21 dB and the stopband extends to 24 GHz (i.e., 5.33f
0
) with a rejection level larger than 22 dB.