【摘要】 介绍了Guanella型传输线变压器的工作原理,利用电报方程分析了其阻抗变换特性和平衡到不平衡转换特性。为在巴伦低阻端获得最佳的输入阻抗,根据测量得到的实频负载阻抗来确定传输线的特性阻抗,设计了在1~30 MHz频带内可用于450Ω到50Ω,600.0Ω到66.7Ω变换的9∶1传输线变压器巴伦。受绕组间距的限制,600.0到66.7Ω巴伦实际的传输线特性阻抗难以达到仿真所要求的值,但巴伦输入阻抗的仿真结果与实测结果仍有较好的一致性。实际测量的结果表明,这两款变压器的工作带宽(驻波比小于1.6)大于30∶1,在1~30 MHz的频带内插入损耗小于0.3 dB。更多还原

【Abstract】 The principle of Guanella-type transmission line transformer(TLT) is presented,and its characteristics of impedance transformation and balance to unbalance transition are analyzed by using the telegraph equation.To obtain the best input impedance at the low impedance terminal of the balun,the characteristic impedance of the transmission line is chosen according to the measured load impedance.Two 9∶1 baluns,which can operate at 1～30 MHz,are designed for 450 Ω to 50 Ω,600.0 Ω to 66.7 Ω transformations,respectively.Because of the narrow interval between windings,the transmission line’s characteristic impedance of the 600.0 Ω to 66.7 Ω balun can hardly achieve the required value by simulation.However,the difference between the measured and the simulated input impedances of the balun is still small.The measured results show that the bandwidths(voltage standing wave ratio less than 1.6) of these two TLT baluns are larger than 30∶1,and the insertion losses are less than 0.3 dB.更多还原