A Novel Approach to the Synthesis of Parallel-Connected Dual-Band Filters

This article presents a novel approach to the synthesis of dual-band filters (DBFs) in parallel-connected topologies. The main challenge is determining suitable transmission zeros (TZs) compatible with the target sparse parallel topology while realizing desired dual-band characteristics. The proposed method involves an iterative process in which the TZs of the DBF are relocated by discarding excessive cross-couplings. The proposed approach offers excellent flexibility in controlling the topology of each parallel-connected single-band filter (SBF). It can be used to synthesize symmetric or asymmetric dual-band filters. Two synthesis examples are provided to demonstrate the effectiveness of the proposed approach.