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一、原理有耗传输线型同轴固定衰减器的原理图如图1所示. 在图1中,区域Ⅰ、Ⅲ为一般的无耗同轴传输线,在区域Ⅱ的内导体表面上有一层电阻薄膜.这层电阻薄膜对通过它的电磁波起衰减作用,因而可以利用它作成衰减器. 假定在区域Ⅱ内具有均匀分布的电阻薄膜,单位长度上的电阻阻值为R,则区域Ⅱ的有耗同轴线特性阻抗Zc为 ?? 上式中,L、C分别为单位长度上的电感量和电容量.Z_(0c)=(L/C)~(1/2)为区域Ⅱ是无耗传输线时的特性阻抗.
First, the principle Lossy transmission line coaxial fixed attenuator schematic shown in Figure 1. In Figure 1, the area Ⅰ, Ⅲ for the general lossless coaxial transmission line, the inner conductor in the area Ⅱ has a layer of resistance Thin film .This layer of resistive film through its attenuation of electromagnetic waves, which can be used as an attenuator. Assuming in the region Ⅱ has a uniform distribution of resistive film, the resistance per unit length is R, then the region Ⅱ Consumption of coaxial cable characteristic impedance Zc ?? ?? Where, L, C, respectively, the inductance per unit length and capacitance .Z_ (0c) = (L / C) ~ The characteristic impedance of the transmission line.