Ⅰ、引言在最近几年中,低噪声微波管方面已经出现了许多重要进展。降低电子注噪声新方法的发现,引起了噪声系数在S波段小于3分贝和在X波段小于4分贝的行波管的发展。最近的分析和实验使电子注噪声现象的知识已显著地丰富起来。通过快波的应用,消除了慢波放大器固有噪声限制的新型放大器已被创制和研究 I. INTRODUCTION In recent years, many important advances have been made in the area of ​​low-noise microwave tubes. The discovery of a new method of reducing the amount of injected electrons has led to the development of traveling-wave tubes with noise figure of less than 3 dB in S-band and less than 4 dB in X-band. Recent analyzes and experiments have significantly enriched the knowledge of electronic noise notation. Newer amplifiers that eliminate the inherent noise limitations of slow-wave amplifiers have been created and researched by fast-wave applications