用于Ka波段行波管的反射式可调预失真线性化器

为了解决目前模拟预失真器存在的可调性差,增益和相位斜率补偿不够的问题,减小预失真器增益扩展和相位扩张之间的相互影响。本文介绍一种工作于Ka波段的反射式模拟预失真电路,该电路基于90°电桥、肖特基二极管、变容二极管产生预失真信号,利用90°电桥的特性实现电路的匹配,同时通过改变肖特基二极管及变容二极管两端的偏置电压实现对预失真电路的增益扩展和相位扩张特性的控制调节。接着对预失真电路进行非线性分析与仿真验证,在此基础上,将所设计的电路加工为实际的预失真线性化器并与Ka波段的空间行波管联合测试,测试结果表明,线性化后的行波管增益和相位特性从之前的-7 dB和-45°改善到-0.5 dB和-3.5°,三阶交调改善了7.5 dB。

Numerical analysis of interaction between solute atom and extended dislocation using force multipoles

The interaction between a solute atom and an extended dislocation was investigated using a continuum approximation method with force multipoles.The dislocation core structure of extended dislocation was modeled with the Peierls-Nabarro model discretized with a number of infinitesimal Volterra dislocations.The interaction energy and force between a nickel solute atom and perfect and extended dislocation in copper were successfully calculated using the force multipoles.The results clearly show that the core structure of extended dislocation weakens the interaction with solute atoms.The interaction energy and force for extended dislocations are almost the half of those for perfect dislocations.