We propose a new tunable coupler with flexible coupling direction and a wide power division ratio (PDR) tuning range. The structure consists of two 90° hybrid couplers with two reconfigurable synthesized transmission lines (RSTLs) inserted in between. The RSTL is designed to operate either in the passband as an analog phase shifter or in the transition region and stopband as a mismatched circuit with tunable reflection/transmission coefficients. By properly controlling the electrical responses of RSTLs, the PDR tuning range can be greatly extended in both forward- and backward-wave coupling operations. The proposed coupler was designed and tested at 2.4 GHz. Our design, among one of few couplers exhibiting switchable coupling paths, yields the widest measured PDR tuning range in both operations while still keeping comparable performance with previous works.

中文翻译：

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具有宽功率分配比调谐范围和灵活耦合方向的耦合器

我们提出了一种新型的可调谐耦合器，它具有灵活的耦合方向和宽的功率分配比（PDR）调谐范围。结构由两个90°混合耦合器组成，两个耦合器之间插入了两个可重新配置的合成传输线（RSTL）。RSTL被设计为在通带中作为模拟移相器工作，或者在过渡带中工作，并且在阻带中工作为具有可调反射/透射系数的失配电路。通过适当地控制RSTL的电响应，可以在前向波耦合和后向波耦合操作中大大扩展PDR的调谐范围。拟议的耦合器是在2.4 GHz下设计和测试的。我们的设计是少数具有可切换耦合路径的耦合器之一，