㈠概述: 在第§1中讨论特性阻抗时,假定电缆是完全均匀的,即沿线各点有完全相同的特性阻抗,但实际上这是不可能的。电缆制造时,不论怎样完漪满地控制,电缆制品的导体直径、绝缘外径总是或多或少存在着变化,而且导体之间也可能出现偏心,再加上绝缘的介电常数也会沿长度而变化,因此在实际的电缆线路上每一点的阻抗都不一定相 (I) General Description: When discussing the characteristic impedance in §1, it is assumed that the cable is perfectly uniform, ie, that there is exactly the same characteristic impedance at each point along the line, but in practice this is not possible. Cable manufacturing, no matter how complete control, cable products, conductor diameter, insulation diameter is always more or less there is a change, but also between conductors may also appear eccentric, coupled with the dielectric constant of insulation will Along the length of the change, so the actual cable line at every point of the impedance are not necessarily phase