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ELECTRICAL TO
ELECTROMAGNETIC
CONVERSION
Electrical energy fed into a
transmitting antenna must be
converted to another form of energy
for transmission.
TRANSDUCER
device that converts energy from one
form to another
EXAMPLES OF TRANSDUCER
LIGHT BULB
ANTENNA
Both converts electrical energy into
electromagnetic energy.
RECEIVING ANTENNA
intercepts the transmitted wave and
converts it back into electrical energy
PHOTOVOLTAIC CELL
A transducer that converts a wave
(light) into electrical energy.
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ELECTROMAGNETIC
WAVES
ELECTROMAGNETIC
WAVES
Waves that are created as a result of
vibrations between an electric field and a
magnetic field.
ELECTRIC FIELD and MAGNETIC FIELD
exist with all electric circuits.
RADIATED ENERGY  UNDESIRED
RADIO-FREQUENCY
INTERFERENCE (RFI)
undesired radiation from a
radio transmitter
ELECTROMAGNETIC
INTERFERENCE (EMI)
unwanted signals from devices that
produce excessive electromagnetic
radiation
TRANSVERSE
when the oscillations of a wave are
perpendicular to the direction of
propagation
POLARIZATION
the direction of the electric field of an
electromagnetic wave
TYPES OF POLARIZATION:
• Linear
- vertical
- horizontal
• Circular – orientation of electric field
- Refers to the orientation
of electric field with
respect to the
Direction of propagation or
with respect to the earth’s
surface.
WAVEFRONT
a plane joining all points of equal
phase in a wave
ISOTROPIC POINT SOURCE
- ISOTROPIC RADIATOR
a point in space that radiates electromagnetic
radiation equally in all directions
POWER DENSITY
- Rate at which energy
passes through a
given surface are in
free space
INVERSE SQUARE LAW
- The power density is
inversely proportional to
the square of the distance
CHARACTERISTICS
IMPEDANCE OF
FREE SPACE
CHARACTERISTIC IMPEDANCE
an attribute of any medium that can
support the transmission of an
electromagnetic wave
POWER DENSITY
STRENGTH OF
ELECTRIC FIELD
POWER DENSITY
CHARACTERISTIC
IMPEDANCE OF FREE SPACE
Characteristic impedance of any
electromagnetic wave-conducting
medium
μ = medium’s
permeability
ϵ = medium’s
permittivity
CHARACTERISTIC
IMPEDANCE OF FREE SPACE
μ=
4
H/m or ϵ =
H/m
F/m
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PROBLEMS
Calculate the power density in watts per
square meter (on Earth) from a 10-W
satellite source that is 22,000 mi from
earth.
mi = 1.609 x 10 m
P = 6.35 x 10 W/
Calculate the electric field intensity, in
volts per meter, 20 km from a 1-kW
source.
E = 0.00866 V/m
or
8.66 mV/m
How many decibels down will that field
intensity be if the distance is an additional
30km from the source?
= 7.96 dB
THANK YOU!
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ALCALA
BALBERAN
BALUYOT
BESHIR
CARIÑO
CASTRO
CUADERNO