A separately-designable diplexer with multiple transmission zeroes (TZs) using common stub-loaded stepped impedance resonator (SIR) is proposed. The common stub-loaded SIR operating in third harmonic (f3) and fifth harmonic (f5) is used for designing the two diplexer channels. The stub is loaded at the voltage-null point of f3 of the SIR. It can separately control f5 but has no effect on f3 so that the two channels can be separately designed. Meanwhile, the input port is tap-connected to the common stub-loaded SIR, which necessarily produces a TZ between f3 and f5, existing in both channel filtering responses. By properly choosing coupling schemes of the two channels, more TZs are realized at the desired locations. Thanks to the generation of the multiple TZs, both passband selectivity and isolation between the two channels are improved significantly. For demonstration, a diplexer operating at 2.22 and 2.95 GHz is designed, fabricated, and measured. The simulated and measured results are presented, showing good agreement.

中文翻译：

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具有多个传输零点的可单独设计的双工器，使用普通短截线加载 SIR

提出了一种可单独设计的具有多个传输零点 (TZ) 的双工器，该双工器使用公共短截线负载阶梯式阻抗谐振器 (SIR)。工作在三次谐波中的常见短截线负载 SIR (F3) 和五次谐波 (F5) 用于设计两个双工器通道。该存根被加载在电压零点F3先生的。可以单独控制F5但对F3这样两个通道就可以分开设计了。同时，输入端口被抽头连接到公共存根加载的 SIR，这必然会在F3和F5，存在于两个通道过滤响应中。By properly choosing coupling schemes of the two channels, more TZs are realized at the desired locations. 由于多个 TZ 的产生，两个通道之间的通带选择性和隔离度都得到了显着改善。为了演示，设计、制造和测量了一个工作在 2.22 和 2.95 GHz 的双工器。给出了模拟和测量的结果，显示出良好的一致性。