Design of E-band High-Isolation and Low-Loss Diplexer

This paper presents our study on high-isolation and low-loss E-band diplexer based on TE201-mode resonators. The diplexer consists of a T-junction and two TX and RX filters, which work at 71-73GHz and 74-76GHz. In addition, by adjusting the offset position and dimensions of the coupling inductive irises, the position of TZs can be flexibly changed. The simulated results show that the maximum in-band insertion loss of each channel filter is 0.35 dB, and the common-port return loss is better than 12 dB. The designed diplexer exhibits a high isolation level larger than 65 dB over the whole band. Therefore, the proposed high-isolation millimeter-wave diplexer is suitable for FDD communication system.