Microstrip Line-based Ultra-Wideband Diplexer Design

For ultrawideband diplexers used in satellite communication systems that span C and X bands, firstly, the diplexer index is split into Tx, Rx filter index, then the Tx, Rx filter satisfying the index is designed using microstrip cross-finger structure and filter synthesis method based on N+2 coupling matrix, and finally the diplexer is further designed using the structure of T-junction and filter combination, and the simulation analysis of this structure of microstrip diplexer is carried out. The simulation results show that the minimum return loss in the diplexer passband is 18.51dB, the maximum insertion loss is 0.99dB, the minimum isolation between passbands is 60.42dB, and the diplexer size is 18mm × 67.0828mm × 0.508mm, which fully meets the index requirements and provides the feasibility of designing high performance diplexer.