Influence of characteristic impedance selection of switching oscillator on output waveform
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摘要: 开关振荡器是宽带高功率电磁脉冲的重要产生方式之一,以开关激励同轴振荡器为例,采用理论计算和电磁仿真为主要手段,从传输线特性阻抗与开关振荡器储能、传输线特性阻抗与天线阻抗关系及传输线特性阻抗和开关导通阻抗关系三个方面进行了研究。研究结果表明:传输线阻抗越小,振荡器储能越高;天线阻抗与传输线阻抗比值越大,输出信号品质因数越大,频谱上能量越集中,带宽越小,能量效率随比值增大呈现先增大后减小趋势;传输线特性阻抗很小时,开关阻抗对输出振荡信号影响增大,此时随特性阻抗减小,输出信号中心频率降低,品质因数减小,频谱上能量分散,带宽较宽。Abstract: Switch oscillator is one of the important methods for broadband high power electromagnetic pulse generation. This paper uses the switch excitation coaxial oscillator as an example, the theoretical calculation and simulation as the main means to study the following three relationships: the characteristics impedance of transmission line and switch oscillator energy storage, the characteristic impedance of the transmission line and the antenna impedance, the characteristic impedance of the transmission line and impedance of switch. The results show that the when characteristics impedance of the transmission line is smaller, the oscillator energy storage is higher; the antenna impedance and transmission line impedance ratio increases, the effective output cycle and quality factor increases, and the energy concentration increases, the spectrum bandwidth reduces, the energy efficiency increases first and then decreases; while the transmission line characteristic impedance is very small, the influence of the switch on the output signal is significant. With characteristic impedance of the transmission line decreasing, the center frequency of the output signal reduces, the quality factor decreases, energy concentration is weak and the bandwidth spectrum expands.
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表 1 k值不同时输出信号的带宽
Table 1. Bandwidth of output signal of variable antenna impedance/transmission line characteristic impedance
k bandwidth/% 20∶1 15.70 15∶1 16.10 10∶1 17.90 5∶1 28.40 2∶1 63.60 -
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