1.导言最近十年间,许多实验室都致力于各种低噪声微波放大系统的研究。在力求减少发射功率和增大作用距离时,在所有远距离发射问题中,减小接收机的固有噪声是极为重要的一个。因此这个问题关系到雷达、无线电中继通讯站、空间通讯和辐射测量等部门。低噪声行波管从1949年诞生以来,在超高频接收机 1. INTRODUCTION In the last decade, many laboratories have focused their research on various low-noise microwave amplification systems. In an effort to reduce transmit power and increase range, reducing the inherent noise of the receiver is of paramount importance in all long-range transmission problems. Therefore, the issue concerns radars, radio relay stations, space communications and radiation measurement. Low-noise traveling-wave tube Since its inception in 1949, the UHF receiver