一、引言当行波管的功率进入中功率范围时,一般都选用环杆结构作慢渡系统。环杆结构的重要特性是:在高电压下场的基波分量具有较高的耦合阻抗,几乎是单螺旋线的二倍,而空间谐波的耦合阻抗却很低,仅为单螺旋线的1/5～1/10,环杆结构具有15～20％的频带宽度,机械强度和散热性能比较好,因此,目前在中功率行波管中获得广泛的应用。 I. INTRODUCTION When the power of the traveling wave tube enters the mid-power range, the ring-rod structure is generally adopted as the slow crossing system. The important features of the ring-rod structure are: the fundamental component of the field at high voltage has a high coupling impedance, almost double the single spiral, but the coupling impedance of space harmonics is very low, only 1 / 5 ~ 1/10, the ring structure has a bandwidth of 15 ~ 20%, mechanical strength and thermal performance is better, so now in the power of traveling wave tube is widely used.