called characteristic resistance. We use the term characteristic resistance
to indicate the impedance of an artificial transmission line.
for characteristic resistance is Rc. As in a real line, the opposition is
equal to the square root of the inductance divided by the capacitance. The
formula is the same as for a real line:
Transmission lines delay voltage.
a. When voltage is applied to the input terminals of a real line, a
definite amount of time passes before the voltage appears at the output.
This is known as time delay (TD). In a real line, the time delay depends
upon the distributed inductance and capacitance per unit length of time and
the length of line used.
The time delay of a real transmission line is
equal to the length of the line times the square root of L and C.
formula for determining the TD of a real line is as follows:
Since the values of L and C per foot are very small, it takes many feet of
real line to delay a pulse just a fraction of a second. For example, let's
use the TD formula to find out how long it takes a pulse to travel along
1,000 feet of line that has a distributed inductance of .2 microhenries, and
a distributed capacitance of 20 uuf per foot. Using the formula, we get: