Abstract In this paper, a balanced-to-balanced (BTB) branch-slotline directional coupler (DC) is firstly presented, which can realize an arbitrary power division ratios (PDRs). The coupler is composed by microstrip-to-slotline (MS) transition structures and branch-slotline coupled structures. The single-ended to balanced-ended conversion is simplified and easy to implemented by the MS transition structures, which intrinsically leads to the differential-mode (DM) transmission and common-mode (CM) suppression. Moreover, the different PDRs which are controlled by the widths of branch-slotlines can be achieved. In order to verify the feasibility of the proposed design method, two prototype circuits of the proposed coupler with different PDRs are fabricated and measured. The return loss and the isolation of two designs are all better than 10 dB. Moreover, the CM suppressions are greater than 35 dB. A good agreement between the simulation and measurement results is observed.

中文翻译：

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一种基于分支槽线耦合结构的平衡对平衡定向耦合器

摘要 本文首先提出了一种平衡平衡（BTB）分支槽线定向耦合器（DC），它可以实现任意功率分配比（PDR）。耦合器由微带槽线（MS）过渡结构和分支槽线耦合结构组成。MS 转换结构简化了单端到平衡端的转换，易于实现，这本质上导致了差模 (DM) 传输和共模 (CM) 抑制。此外，可以实现由分支槽线宽度控制的不同PDR。为了验证所提出的设计方法的可行性，制造并测量了所提出的具有不同 PDR 的耦合器的两个原型电路。两种设计的回波损耗和隔离度均优于 10 dB。此外，CM 抑制大于 35 dB。观察到模拟和测量结果之间的良好一致性。