This letter presents a high isolation substrate integrated waveguide (SIW) diplexer using dual-mode resonators. Each dual-mode SIW resonator can generate one transmission pole (TP) and one transmission zero (TZ) for the channel filter. The frequencies of the TZs can be easily controlled by the perturbation vias. One channel filter’s two TZs’ frequencies are designed to cover the other channel filter’s passband. Thus, high isolation performance is achieved. The proposed diplexer is designed and fabricated with lower and upper channels centered at 8.04 and 9.07 GHz, respectively. Simulated and measured results are in good agreement for the two channels with better than 49/53-dB channel isolation.

中文翻译：

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具有灵活传输零点的高隔离基板集成波导双工器

这封信介绍了一种使用双模谐振器的高隔离衬底集成波导 (SIW) 双工器。每个双模 SIW 谐振器可以为通道滤波器产生一个传输极点 (TP) 和一个传输零点 (TZ)。TZ 的频率可以通过微扰通孔轻松控制。一个通道滤波器的两个 TZ 频率旨在覆盖另一个通道滤波器的通带。因此，实现了高隔离性能。所提出的双工器设计和制造的下通道和上通道分别以 8.04 和 9.07 GHz 为中心。两个通道的仿真和测量结果非常吻合，通道隔离度优于 49/53-dB。