- Physics:
- When an electrical signal (= electricity) traverse through a copper wire, the always lose some power
Graphically:
Terminology:
- Attenuation = loss of power
- There are 2 ways
that an electrical signal
can
lose power:
- Resistance (in the wire):
Resistance in the wire will cause some of the energy in the signal to be converted into heat
- Radiation:
When the frequency of the electric current is very high, an alternating current will generate a strong electro-magnetic field.
The wire will work like an antenna - and some energy of the signal will radiate away....
- Resistance (in the wire):
- Fact from
Physics:
- The amount
of power loss
depends on:
- The resistance
of the transmission medium
- The frequency of the electro-magnetic signal (= how much of the power will radiate away).
- The resistance
of the transmission medium
- The amount
of power loss
depends on:
- The energy loss characteristics
is as follows:
- When the
(alternating) electric current
has a
very low frequency:
- the current
encounters
high electrical
resistence.
(DC current generates a low of heat !!!!)
Result:
- A large portion of the energy in the transmitted signal is lost because the energy is converted into heat
- the current
encounters
high electrical
resistence.
- When the
(alternating) electric current
has a
very high frequency:
- the current will generate a strong electro-magnetic field.
Result:
- A large portion of the energy in the transmitted signal is lost because the energy is converted into electro-magnetic wave (radiation)
- When the
(alternating) electric current
has a
very low frequency:
- Energy loss characteristic
of a wire transmission medium is
as follows:
