Types of Transmission Lines

1. Academic year 2018-19
EC6503 – Transmission Lines
And Wave Guides
Types of Transmission Lines
Mrs.R.Chitra, AP/ECE,
Ramco Institute of Technology,
Rajapalayam

2. Introduction
• Electromagnetic energy generated in one place, has a
natural tendency to spread in the whole space.
• In a telecommunications, this behavior can be useful,
when the user position is not known in advance, as in
a broadcasting system or in a cellphone network.
• In other applications, electromagnetic energy must be
transferred from one place to the other along well
defined path without any spreading at all. Ex. Cabling
of building.

3. Contd…
• In most general terms, transmission line is a system
of metal conductors and (or) dielectric insulating
media that is capable of guiding the energy transfer
b/w a generator and a load.
• Transmission line is defined to carry alternating
current of radio frequency, that is, currents with
frequency high enough that their wave nature must be
taken into account.
• Electromagnetic radiation can be contained and
guided within structures called transmission lines.

4. Differences Between a Power-Line Cable
& a Phone Line
Sl.
No.
Power-Line Cable Phone Line
1. Transmitting power Transmitting phone signals
2. Power cables are exclusively one-
way: they relay power from the
point of origin to various buildings
and homes on the power grid.
Telephone lines are responsible for two-
way communication and must relay
phone signals both to and from a building
or home to facilitate conversation.
3. Power cables have a much higher
energy outlet level than do
telephone lines. The reason for this
is that power cables must relay
enough power from the source to
various recipients to power all of
the homes and buildings along the
cables' route. Thus at any given
point in time or space, a power
cable is relaying enough electricity
to power several buildings.
Telephone lines don't provide electricity.
Rather, they transmit signals. The power
output of telephones lines is only enough
to relay a phone signal and is thus very
low.

5. Contd…
Sl.
No.
Power-Line Cable Phone Line
4. Power cables are most commonly
built of aluminum that is surrounded
by steel. Aluminum is a tremendous
conductor of electricity but is very
weak. In power cable construction,
steel cables designed to protect the
aluminum from strong winds, ice and
other elements surround a central
aluminum conductor.
Telephone cables are made from copper
and which are used to transmit television
signals in addition to telephone signals.

6. Types of Transmission lines

7. Open wire line (Parallel wire line)

8. Contd…

9. Twisted Pair Line (Cables)

10. Contd…

11. Contd…

12. Co-axial line

13. Contd…

14. Wave Guides
Circular Waveguide
Rectangular Waveguide

15. Optical fibers

16. Transmission line parameters

17. Contd…

21. References:
 John D Ryder, “Networks, lines and fields”, 2nd Edition,
Prentice Hall India, 2010.
 E.C.Jordan and K.G. Balmain, “Electromagnetic Waves
and Radiating Systems”,Prentice Hall of India, 2006.
 G.S.N Raju "Electromagnetic Field Theory and
Transmission Lines”, Pearson Education, First edition
2005.