This slide created by Abdullah Al Mehedi about Antenna Radiation pattern. Bandwidth, Directivity, Efficiency, Gain.

1. Radiation Pattern
Abdullah Al Mehedi
ID- 150105
Section- A
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2. Radiation Pattern
◦ Beamwidth
◦ Pattern Solid Angle
◦ Directivity
◦ Efficiency
◦ Gain
Radiation pattern
Directional Radiation
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3. Beamwidth
Antenna Beam width is the angle between
the half-power of an antenna pattern or
beam over which the relative power is at or
above 50% of the peak power.
 Known as half-power.
Beamwidth = 70λ / D
where,
λ = Wavelength
D = Diameter
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4. Beamwidth
3D Radiation Pattern.
Polar Radiation Pattern
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5. Antenna Pattern Solid Angle
sin .d d d   
A differential solid angle,
d, in sr, is defined as
2
0 0
sin 4 ( ).d d sr
 
 
   
 
   
For a sphere, the solid angle is found by
integrating
An antenna’s pattern solid angle,
 ,p n
P d   
All of the radiation emitted by the antenna is
concentrated in a cone of solid angle p over
which the radiation is constant and equal to the
antenna’s maximum radiation value. 5

6. DIRECTIVITY
 Fundamental antenna parameter.
 Measurement of radiation pattern
 Equally in all directions would have
effectively zero directionality,
 Directivity of equally directional
antenna would be 1.
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7. DIRECTIVITY
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Directivity
Normalized radiation pattern can be written
as a function in spherical coordinates:

8. Efficiency
Power is fed to an antenna through a T-Line and
the antenna appears as a complex impedance
.ant ant antZ R jX 
ant rad dis
R R R 
radiation
dissipativeFor the antenna is driven by phasor current j
o sI I e 

Power dissipated by ohmic losses is 21
2
diss o diss
P I R
rad rad
rad diss rad diss
P R
e
P P R R
 
 
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9. Gain
   , ,G eD   
The power gain, G, of an antenna is very
much like its directive gain, but also takes
into account efficiency
The maximum power gain max maxG eD
The maximum power gain is often
expressed in dB.
   max max10
10logG GdB 
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10. ?
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