Abstract Three-stub waveguides are common impedance matching devices which are essential for a wide range of high-power microwave applications. Based on equivalent circuit analysis method, this article presents a novel matching algorithm which can be applied for three-stub tuners to implement continuous, automatic and real-time impedance matching. Equivalent model of a stub waveguide is firstly established by using transmission lines in series and capacitors in parallel. Then, according to the proposed model, the mathematical expression of reflection coefficient at different stub depth is derived by using currently detected reflection coefficient and stub depth. Later, based on the derived expression, an algorithm is developed to determine the optimum insertion depths of the stubs when VSWR is minimum. The S 11 parameters of the stub waveguide which are calculated by the method agree well with those measured by vector network analyser. Meanwhile, the algorithm is able to limit reflection coefficient under –10 dB and can easily be redesigned for waveguides of different sizes. Thus, it shows a promising future in industrial impedance matching applications.

中文翻译：

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基于等效电路分析的三短截线调谐器动态阻抗匹配算法

摘要 三短节波导是一种常见的阻抗匹配器件，对于广泛的高功率微波应用至关重要。本文基于等效电路分析方法，提出了一种新颖的匹配算法，可用于三短管调谐器实现连续、自动、实时的阻抗匹配。首先利用串联传输线和并联电容器建立短波导管的等效模型。然后，根据所提出的模型，利用当前检测到的反射系数和短截线深度，推导出不同短截线深度处反射系数的数学表达式。随后，基于导出的表达式，开发了一种算法来确定当 VSWR 最小时短截线的最佳插入深度。该方法计算得到的短波导S 11 参数与矢量网络分析仪测得的参数吻合较好。同时，该算法能够将反射系数限制在 –10 dB 以下，并且可以针对不同尺寸的波导轻松重新设计。因此，它在工业阻抗匹配应用中显示出广阔的前景。