Conventionally, diplexers are designed by connecting two filters of different frequencies using a transmission T‐line junction which acts as a distribution network serving the individual filters. Here, a novel diplexer has been proposed and designed to utilize a directly coupled resonator as the distribution network. The directly coupled resonator is designed using two square open‐loop resonators of the same resonant frequency of 1.95 GHz. Coupling of the two resonators is achieved using a λ/4 transmission line to directly couple them. This process made the resonator pair to possess a dual‐mode resonator function, resonating at 1.85 and 2.05 GHz. Two bandpass filters are then designed in the corresponding modes of the resonator pair with 5% fractional bandwidth and coupled accordingly. This technique allowed the resonator pair to contribute to the resonant poles of the diplexer while functioning as the distribution network.

中文翻译：

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具有直接耦合谐振结的双工器

通常，双工器是通过使用传输T线结连接两个不同频率的滤波器来设计的，该T形结充当服务于各个滤波器的分配网络。在此，已经提出并设计了一种新颖的双工器，以利用直接耦合的谐振器作为分配网络。直接耦合谐振器是使用两个谐振频率为1.95 GHz的方形开环谐振器设计的。两个谐振器的耦合通过使用λ/ 4传输线直接耦合来实现。此过程使谐振器对具有双模谐振器功能，在1.85 GHz和2.05 GHz频率下谐振。然后在谐振器对的相应模式下设计两个带通滤波器，带宽为5％，并进行相应耦合。