Planar Balanced and Single-Ended Dual-Path Filtering Crossover With Enhanced Isolation and Frequency Selectivity

In this letter, a novel high-performance planar balanced and single-ended dual-path (BSDP) filtering crossover is proposed, which achieves not only cross-transmission and great common-mode (CM) suppression but also enhanced isolation and frequency selectivity. The constraint rules of S-parameters are provided, and the circuit structure is simplified and analyzed based on the classical even- and odd-mode method. The freely selected electrical parameters of the BSDP crossover are considered and explored to control the filtering transmission bandwidths of the balanced path and single-ended (SE) path, independently. To verify the viability of this design, a microstrip prototype is manufactured and measured with enhanced wideband isolation and sharp filtering selectivity.