Wideband Bandpass Filters with Improved Selectivity using Coplanar Stripline-Based Stub-Loaded Resonators

In this paper, a type of wideband bandpass filters (BPFs) with enhanced selectivity is presented by using the proposed coplanar stripline (CPS)-based stub-loaded resonators (SLRs). With resorting to the typical even-odd mode analysis, the multimode mechanism of the proposed SLRs could be explicated. Topologized design is then carried out to transform the BPFs into the composite-stub topology, which can be intuitively helpful for synthesis design as well as the justification of enhanced selectivity. Finally, the CPS-based BPFs are designed and simulated, showing better roll-off of the passband due to the introduction of more higher-order transmission zeros (TZs) and a pair of finite TZs.