Filtering Power Divider with Wide Stopband Using Open-Stub Loaded Coupled-Line and Hybrid Microstrip T-Stub/DGS Cell
In this paper, a compact filtering Wilkinson power divider exhibiting the high isolation with an ultra-wideband spurious suppression is proposed. The open-stub loaded coupled-line (OSLCL) is introduced for the power divider design to obtain the passband enhancement with two transmission zeros close to center frequency of f0. Besides, hybrid microstrip T-stub/defected ground structure (HMT/DGS) cells are employed to introduce intrinsic slow-wave effect, which leads to the performance of high isolation and rejection level within a wide stopband. To verify the mechanism mentioned above, a filtering power divider operating at f0 of 2.31 GHz with 3-dB FBW of 17.7% is implemented and fabricated. The measurement exhibits more than 28 dB stopband isolation and 30 dB stopband rejection level up to 20 GHz (i.e., 8.66f0).