A Six-stub Strip Line Impedance Tuner

Solid-state sources have gained significant momentum and have been widely adopted across various fields due to their numerous advantages that surpass those of magnetron tubes. This paper proposes a six-stub strip line impedance tuner, which can be applied for solid-state sources to achieve maximum power transfer and prevent damage from large reflection. The tuner is composed of three parts, which are tuning unit, impedance conversion unit and feeding interface unit. The tuning unit is designed based on the principle of equivalent circuits, the stubs are designed in a symmetrical manner to increase the value of the equivalent capacitance and enhance power capacity. A quarter-wavelength impedance transformer is used to transform the impedance to 50 Ω, and then a well-designed 50 Ω feed port is used to match the source end. The depth of the stubs is calculated using an equivalent circuit method, and simulation results validate that |S11| < -15 dB, achieving a good matching effect. This tuner can be used for automated tuning in industrial applications.