一种结构新颖的微带前向耦合器设计及其应用
A novel structure of microstrip forward coupler and its application

定向耦合器在微波系统中应用广泛，而关于前向耦合器的研究甚少。介绍了一种中心频点在2.45GHz的微带线前向耦合器设计方法。该方法通过引入两条耦合平行线和不对称延迟线，既提高了耦合平坦度和隔离度，也避免了传统设计中因渐变线的引入而导致结构尺寸变大的缺陷。同时，基于该前向耦合器设计加工了一种探测流动溶液微弱介电特性改变的多端口射频电路，实验结果证明了该耦合器的可靠性。
Most reports in the published literature concentrated in the backward couplers, while little attention has been paid to forward couplers. In this paper, we propose a novel single-sectioned microstrip line forward coupler, which consists of parallel coupled lines and asymmetrical delay lines. The operation frequency is chosen as 2.45GHz. The simulation results show, by proper design of some structural parameters, such as the length of coupling lines and delay lines, the designed structure enables the coupler to enhance the coupling and directivity, as well as to avoid the enlargement size of the coupler owing to the introducing of the tapered lines. Based on the well-designed coupler above, we have further designed a multi-ports microwave network circuit. The tested and experimental results show the reliability of the forward coupler