Dual-Mode Diplexer With High Isolation Based on Amplitude and Phase Cancellation Technique

Abstract

This paper presents a dual-mode diplexer with easy fabrication and high signal isolation based on amplitude and phase cancellation technique. The dual-mode structure enables a compact and easy asymmetrical frequency response which also requires considerable attenuation between the proximity in frequency of the transmitter and that of the receiver. Two back-to back dual-mode threeport diplexers and a 180 • phase shifter are easily employed to construct the proposed device, which are combined to form a four-port dual-mode diplexer. A 180 • phase shift in one branch can be achieved by delayed transmission line. The simulated and measured four-port dual-mode diplexers are designed at the operational frequency of Tx/Rx at 1.95 GHz and 2.14 GHz, respectively. The measured results of Tx/Rx dual-mode diplexer devices are presented of 48.5 dB Tx/Rx isolation. This four-port dualmode diplexer achieves the isolation (S 32) more than 21.5 dB compared with a conventional three-port dual-mode diplexer.

Four-Port Dual-Mode Diplexer with High Signal Isolation

“…e realized microstrip filter prototype with small circuit size can be achieved by this technique. e technique for size reduction and high isolation signal by using a dual-mode resonator filter and diplexer is presented in [14,15]. In this paper, an ease of four-port dual-mode diplexer with high signal isolation is presented.…”