In this article, a class of improved Schiffman phase shifters with two C-section coupled lines separately operating in the first and second phase periods is presented and analyzed. Theoretical model and closed-form synthesis formulae are utilized to analyze the phase performances of the proposed phase shifters, which reveals significant differences compared to the phase shifters solely operating in the first or second phase period. Compared to the traditional counterparts, the proposed phase shifters can achieve a larger phase shift value and a wider phase shift range at the same impedance ratio. Moreover, under the same impedance ratio, the phase shifter can obtain wider phase shift bandwidth. These features are believed to be very useful in the limitedly realizable coupling strength for a wide phase shift range case. Finally, two sets of comparative experiments, including the operations in the first phase period, second phase period, and the proposed type, are designed and fabricated to validate the proposed approach. The simulated and measured results agree well with the theory and achieve a 33.6% (36.7%) increase in phase shift bandwidth when the phase shift value is 90° (150°) under the impedance ratio of 1.5822 (2.0312).

中文翻译：

---

在耦合线的第一和第二相周期操作下具有宽相移范围的希夫曼移相器

本文介绍并分析了一类改进的希夫曼移相器，该移相器具有两条 C 截面耦合线，分别工作在第一和第二阶段。利用理论模型和闭式综合公式来分析所提出的移相器的相位性能，与仅在第一或第二阶段工作的移相器相比，该移相器具有显着差异。与传统的对应物相比，所提出的移相器可以在相同的阻抗比下实现更大的相移值和更宽的相移范围。而且，在相同的阻抗比下，移相器可以获得更宽的移相带宽。这些特征被认为对于宽相移范围的情况在有限可实现的耦合强度中非常有用。最后，设计并制作了两组对比实验，包括第一阶段、第二阶段和所提出的类型的操作，以验证所提出的方法。仿真和实测结果与理论吻合较好，在阻抗比为1.5822（2.0312）的情况下，相移值为90°（150°）时，相移带宽增加了33.6%（36.7%）。