高隔离度Ka波段平面魔T的设计

提出了一种适合于毫米波微波集成电路(M IC)的高隔离度平面魔T结构,该结构属于一种新型的180°平面型混合网络。基于传统的微带混合环原理,引入了微带-槽线过渡的结构,两个端口之间的180°相移通过微带-槽线转换结构实现,从而实现了输出端口的隔离。该结构采用多节阻抗匹配网络,增加了工作带宽,使微带-槽线过渡结的寄生耦合最小化。通过设计可实现得到最小尺寸的槽线终端,降低了微带-槽线过渡结的辐射损耗。引入的等效电路模型有效地提高了平面魔T的设计。借助CST软件,仿真优化了λg/4变换器以及微带-槽线转换结构的阻抗匹配,提高了隔离度。实验结果表明:在工作带宽(34～36 GHz)内,该结构输出端口2和3的隔离度达20 dB,输入端口回波损耗低于18 dB,插入损耗1 dB。

Design of High Isolated Ka Band Planar Magic-T

A high isolated planar Magic-T was presented which was appropriate for MIC.This structure belonged to a novel 180°planar hybrids configuration.It was designed based on the traditional principle of microstrip hybrid ring and introduces microstrip-slotline tee junction.The 180°phase shift of the two ports was realized by the transition of microstrip-slotline which the isolation of output ports was realized.A multisection impedance transformation network was used to increase the operating bandwidth and minimize the parasitic coupling around the microstrip-slotline tee junction.The design implemented a small microstrip-slotline tee junctions with minimumsized slotline terminations to reduce radiation loss.Derived equivalent circuit models were used efficiently for the design of the planar Magic-T.The λg/4 impedance transformer and the impedance matching of the microstrip-slotline tee junctions were simulated and optimized by CST to achieve higher isolation.The experimental results show that the structure provides the isolation of 20 dB with the insertion loss of 1dB in the bandwidth of 34-36 GHz.The return loss is got less than 18 dB at input put.