to current flow. Coaxial lines are more difficult to construct than other
types of transmission lines.
As a result, they are more expensive.
The
characteristic impedance of coaxial lines ranges from approximately 10 to
150 ohms.
The diameter of the conductors determines the characteristic
11. Review of transmission line types.
The following chart summarizes the main points to remember about the
different transmission lines.
Notice that the waveguide appears at the
bottom of the chart. The waveguide is a special type of transmission line
used at frequencies above 3000 megahertz.
Waveguides are discussed in
lesson four.
Figure 6.
Types of Transmission Lines.
12. A transmission line is similar to ordinary circuits.
a. To begin our detailed study of transmission lines, first consider
what they are: Wires!
When you study circuits such as multivibrators,
blocking oscillators, and other circuits, you use a schematic. You analyze
these circuits in terms of current and voltage. The use and understanding
of symbols in the schematic to represent resistors, capacitors, inductors,
and vacuum tubes makes the circuit more logical and easier to understand.
In transmission lines, all we have are wires. This means that we will have
to consider transmission lines in some manner that will make them more
logical and easier to understand.
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