|
原文是这样讲的:( a$ D! q3 i) {6 A5 w
The impact from the losses is to slow down the lower frequencies more than) C0 B4 B8 R4 `" o W
the higher frequencies. At lower frequencies, the series resistive impedance domi-
2 x# Z, a* G( c$ K8 ^& w/ z9 F* Knates over the series reactive impedance from the loop inductance. As well,9 r* N5 }! E4 V7 K
the line looks more lossy and the signal speed is reduced. When speed varies with2 _7 Z0 I5 ~! Z& C
frequency, we call this dispersion. It arises from two mechanisms: frequency-
7 {; [ O, n$ Y' ndependent dielectric constants and losses. 9 _: y/ H; a3 `' ]7 E
意思是低频下,有损等效模型中的串接电阻特性带来的延时效果会比等效环路电感带来的延时效果要强,所以低频的信号通过时在线上的损耗要大些。
* _+ c5 r7 F3 |) ~, t- A这是因为较低频率下,有损线的感性体现出来的电抗omega*L与串接电阻的模相比较要远远不及,形成的延时接近于RC延时。
' i) d8 A( m0 x$ t' e! M" }高频下,介质上的感性表现的电抗会比电阻大的多,这时的延时在损耗不大的情况下接近于Z0*C=sqrt(L*C)! c- B# a9 Z ~/ C* C) _2 b$ d U
1 T3 d+ i! ]1 j/ Q' h9 v L
* y9 }) h' F+ X4 }- O3 g, {/ ]" V
|
|