High Signal Isolation Dual-mode Diplexer Using Square Loop Resonator with Tuning Stub

This article introduces a high signal isolation dual-mode diplexer. The diplexer circuit's configuration incorporates two independently designed dual-mode filters, each capable of determining the position of the transmission zero (Tz). When interconnected to form a dual-mode diplexer circuit, it is demonstrated that this configuration exhibits superior isolation values compared to conventional diplexer circuits, particularly when positioned at the specified Tz location. The proposed dual-mode diplexer is designed for frequencies of 1.95 GHz and 2.14 GHz, delivering isolation surpassing 70 dB and insertion losses better than 1.1 dB in both channels.