Parabolic Antenna : *Intro *idea of design *types *parabolic reflector *Application *features

1. Parabolic Antenna
Presentation In

2. What is Parabolic Antenna
?
• A parabolic antenna is an antenna that
uses a parabolic reflector ,or a curved
surface with the cross-sectional
shape of parabola, to direct the radio
waves.
• It is often referred to as a dish
antenna.

3. Parabolic Reflector
• The reflector can be of sheet metal, or wire grill
construction it can be either circular “dish” or various shape
to create different beam shapes. Its size means that it is
generally limited to use above 1GHz, although larger
antennas may be used for frequencies down to about
100MHz.the parabolic reflector antenna or dish antenna
is known for its distinctive shape, its high gain, and narrow
beamwidths.

4. Cont-Parabolic
Reflector

5. Idea of design &
Composition
• The operating principle of a parabolic antenna : is that the
radio waves at the focal point in front of a paraboloidal
reflector of conductive material will be reflected into a
collimated plane wave beam along the axis of the
reflector. Conversely, an incoming plane wave parallel to
the axis will be focused to a point at the focal point.
Focal length : The focal length of a parabola is the distance from its focus to its vertex

6. Types of parabolic Antenna
•Parabolic Antenna is classified by their shapes to :
• Parabolodial or dish : This is the most
common type.
It radiates a narrow pencil-shaped
beam.

7. Types of parabolic Antenna
•Shrouded Dish :
The shrouded shields the
antenna from radiation
from angles outside the
main beam axis ,
reducing the side lobe .
Shrouded microwave relay dishes on a
communications tower in Australia.

8. Types of parabolic Antenna
•Cylindrical :
The reflector is curved in
only one direction , and flat
in the other .
The radio waves come to a
focus not at a point but
along a line .
Early cylindrical parabolic
antenna,1931,Nauen,Germany .
Focus-The focus is where all the incoming radio waves are concentrated.

9. Basic types of Parabolic
Antenna

10. Antenna Gain
•Gain : is the ratio of the power received by the antenna from
a source along its beam axis to the power received by an
isotropic antenna .
The gain of parabolic antenna is :
AA e
d
e
2
2
A4
G 










Where :
A : is the area of the antenna aperture, that is, the mouth of the
parabolic reflector. For a circular dish antenna
d : is the diameter of the parabolic reflector, if it is circular .
: The aperture efficiency of typical parabolic antennas is 0.55
to 0.70.
Ae
.
4
2
d
A



11. Features of parabolic
antenna
Greater directivity and Gain .
Parabolic or dish antennas are NOT
frequency dependant .
Receives and radiates signal in one direction
only .
Produce sharp and narrow beam width of any
antenna types .
Handy for end users ( small reflector
antennas ) .

12. Applications
Parabolic antennas are used as :
High gain antennas for point to point
communication.
In applications such as microwave relay links that
carry telephone and television signals between nearby
cities.
Wireless WAN/LAN links for data communications
satellite and spacecraft communication antennas.
Radio telescopes.
Radar antennas.
Satellite television dish antennas .

13. Presented By :
1. Omar Hussein Mohamed .
2. Mo’emen Mohamed abdelshafy .
3. Amr Mohamed mahrous .
4. Kareem Abdel Ghany .
End
Thank you