卫星互联网用空间行波管非线性特性模拟

为了研究卫星互联网用空间行波管的非线性特性，本文使用行波管一维大信号模型，结合CST软件计算得到的行波管冷特性参数，基于MATLAB平台编写了数值计算程序。使用所编写的程序，以Ka波段和Q波段的两种空间行波管为模型，计算其调幅-调幅（AM-AM）和调幅-调相（AM-PM）的主特性，并同时计算了三阶交调失真（IMD3）和噪声功率比（NPR）。分析了输入功率的回退对这两种非线性特性的影响，并与矢量网络分析仪得到的实际测试结果进行了对比，三阶交调的计算结果与实际测试的误差在1dB以内。为高线性度行波管的设计提供模拟工具。

Simulation of Nonlinear Characteristics of Space Traveling Wave Tubes for Satellite Internet Application

In order to study the nonlinear characteristics of space traveling wave tube(TWT)for satellite internet application,a numerical calculation program was written on the MATLAB platform using an improved one-dimensional largesignal model combined with the cold characteristics parameters of TWT calculated by CST.Using the written program,the main characteristics of amplitude modulation-amplitude modulation(AM-AM)and amplitude modulation-phase modulation(AM-PM)are calculated based on the model of two kinds of space TWT(Ka-band and Q-band).In parallel,third-order intermodulation distortion(IMD3)and noise power ratio(NPR)were also calculated.The effect of input power back-off on these nonlinear characteristics are analyzed and compared with the actual test results from a vector network analyzer,where the discrepancy between the calculated and test results is within 1 dB.A simulation tool is provided for the design of high linearity TWTs.