2026/07/25 by Jose Luis Medrán del Río, Armando Fernández‐Prieto, Jesús Martel +1
paper · doi:10.1049/ell2.70661
ABSTRACT Balanced‐to‐balanced (B–B) diplexers must simultaneously provide selective differential‐mode (DM) signal distribution and strong common‐mode (CM) suppression. Classical T‐junction‐fed architectures offer limited control of channel isolation and filtering response, while input‐overcoupled‐resonator‐based solutions are only suitable for closely spaced passbands. This letter presents a new B–B diplexer topology in which embedded resonators are employed as a common input feeding stage. Each resonance frequency of the input structure directly excites one output channel, enabling diplexing operation with widely separated passbands while maintaining proper differential‐mode transmission and strong common‐mode suppression. This architecture enables independent tuning of widely separated passbands, without relying on conventional T‐junction‐based approaches or synchronous resonant behaviour, and provides improved CM rejection and channel‐to‐channel isolation. A fully planar prototype is designed, fabricated and measured.