衬底型五级超宽带带状线耦合器的设计

Design of 5-stage ultra-wide-band stripline coupler with underlay structure

设计一种0．35～3．80GHz频段的6dB五级超宽带祸合器．耦合器前两级采用衬底型平行耦合带状线结构，后三级采用传统侧边耦合带状线结构．在带状线级联处加载客性开路膜片补偿电路，改善电路的匹配性能，降低器件的回波损耗．衬底型紧褐合结构克服了印刷电路工艺对耦合带状线线间距的限制，且不需要高分辨率的制作过程，也不会引入焊点等不连续性结构．仿真的耦合系数和实测数据有较好的一致性．

A 6-dB coupler worked in 5-stage ultra-wide-band from 0. 35 to 3.8 GHz was designed. In this coupler, first two stages had underlay structure and following three stages were of conventional sided coupling stripline structure. A capacitive opened film compensating circuit was loaded at the cascade spots of the striplines for improving the matching performance of the circuit and reducing the return loss of the device. By using this underlay tight coupling structure, the limits on the interval of coupling striplines with printed circuit processing were overcome, a high resolution was unnecessary for device fabrication, and the discontinuity in the circuit such as the wire bonding would not occur. The measured coupling coefficient showed a good agreement with that of electromagnetic simulations.