TABLE #2

(2) Values for distributed constants. Values for

distributed constants of commonly open-wire lines and

nonloaded cables are given in Table #2 below. Note that

as the wire diameter of an open-wire line increases the

series resistance decreases appreciably and the series

inductance decreases only slightly.

The shunt

capacitance increases slightly and the shunt conductance

does not change. This is because the shunt conductance

is actually leakage conductance and depends only on

the nature of the insulating material separating the wires. In the case of cables, only the series resistance decreases as the

wire size increases (lower gage number), the other constants remaining essentially constant.

59.

Characteristic Impedance.

The characteristic impedance, ZO, of

a network is the value of load impedance which

makes the impedance at the input terminals

of the network equal to the load impedance.

The tee and pi sections of figure 55 help

to explain this. For example, in the tee section

of A, the load impedance, ZR, is 600 ohms.

This resistor is in series with the right-hand

FIGURE 55. Tee and pi Sections Terminated in Zo.