In this paper, a wideband crossover is presented based on the typical 2×2 distributed window‐shaped structure. By loading extra stepped‐impedance open stub at each port, three reflection zeros could be generated within the operating band for bandwidth enhancement, while three transmission zeros are introduced for isolation improvement. Two additional transmission zeros at through port are also generated to enhance the out‐of‐band attenuation. By properly adjusting the physical width and length of the stubs, a wideband response with equal reflection ripples can be achieved. As an experimental verification, a prototype of the designed microstrip crossover at 2.4 GHz is implemented and fabricated. The measured results have a good agreement with those obtained from simulation. The measured fractional bandwidth of 1 dB insertion loss achieves 38.7% and the measured 15 dB return loss bandwidth is about 39.2%, while the measured 15 dB isolation bandwidth reaches 40.0%.

中文翻译：

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修改后的基于窗口形状的分频器，具有增强的带宽

本文基于典型的2 ×2分布式窗口状结构。通过在每个端口上加载额外的步进阻抗开路短截线，可以在工作频带内生成三个反射零点，以增强带宽，同时引入三个传输零点以改善隔离度。在直通端口处还会产生两个额外的传输零，以增强带外衰减。通过适当地调整短截线的物理宽度和长度，可以实现具有相等反射波纹的宽带响应。作为实验验证，设计并制造了2.4 GHz设计的微带分频器的原型。测量结果与仿真结果吻合良好。测得的1 dB插入损耗的小数带宽达到38.7％，测得的15 dB回波损耗带宽约为39.2％，