The problem of obtaining a wideband equivalent circuit for dipole antennas is addressed backward; the four-element circuit topology is taken as given; its three-element part was suggested by Chu and its extension to four elements by Stuart. The goals here are to obtain the element values with the least effort and to explore the available bandwidth. Based on the impedance spectrum, rather than on radiation or current eigenmodes, this approach identifies elements of the circuit from their behavior with frequency over a wideband impedance spectrum that includes both first and second resonances. Element values are derived from their impedance behaviors at three frequencies: zero (dc), first (series or short-circuit), and second (parallel or open-circuit) resonance. An Argand diagram is introduced to determine ${R}$ and ${L}$ at the first resonance; the two capacitances, ${C}$ and ${C} _{t}$ , at first and second resonances, respectively, complete the circuit. Optimization follows. Several examples are given and limitations discussed.

中文翻译：

---

电偶极子的宽带等效电路

获得偶极天线的宽带等效电路的问题是反向解决的；采用四元件电路拓扑结构；它的三元素部分是由楚提出的，而斯图亚特则将其扩展为四元素。此处的目标是以最少的努力获得元素值并探索可用带宽。该方法基于阻抗谱，而不是辐射或电流本征模式，根据电路元件在包括第一和第二谐振的宽带阻抗谱上的频率行为来识别它们。元件值源自它们在三个频率下的阻抗行为：零 (dc)、第一次（串联或短路）和第二次（并联或开路）谐振。引入Argand图来确定 ${R}$ 和 ${L}$ 在第一次共振时；两个电容， ${C}$ 和 ${C} _{t}$ ，分别在第一次和第二次谐振时完成电路。优化如下。给出了几个例子并讨论了限制。