ELECTRONICS AND COMMUNICATION ENGINEERING
ANTENNAS AND WAVE PROPAGATION
TWO MARK QUESTIONS
1. Define an antenna.
Antenna is a transition device or a
transducer between a guided wave and a free space wave
or vice versa. Antenna is also said to be an impedance
transforming device.
2. ...
TWO MARK QUESTIONS
1. Define an antenna.
Antenna is a transition device or a
transducer between a guided wave and a free space wave
or vice versa. Antenna is also said to be an impedance
transforming device.
2. What is meant by radiation pattern?
Radiation pattern is the relative distribution
of radiated power as a function of distance in space .It is a
graph which shows the variation in actual field strength of
the EM wave at all points which are at equal distance from
the antenna. The energy radiated in a particular direction by
an antenna is measured in terms of FIELD STRENGTH.(E
Volts/m)
3. Define Radiation intensity?
The power radiated from an antenna per unit
Prepared by : LENIN RAJA, Assistant Professor / Research Coordinator,
Sri Vidya College of Engineering & Technology, Virudhunagar, Tamilnadu.
Mail to: leninaucbe@gmail.com; lenin.svcet@gmail.com
,solid angle is called the radiation intensity U (watts per
steradian or per square degree). The radiation intensity is
independent of distance.
4. Define Beam efficiency?
The total beam area ( WA) consists of the
main beam area ( WM ) plus the minor lobe area ( Wm) .
Thus WA = WM+ Wm .
The ratio of the main beam area to the total
beam area is called beam efficiency.
Beam efficiency = SM = WM / WA.
5.Define Directivity?
The directivity of an antenna is equal to the
ratio of the maximum power density P(q,f)max to its
average value over a sphere as observed in the far field
of an antenna.
D = P(q,f)max / P(q,f)av. Directivity from
Pattern.
D = 4p / WA. . Directivity from beam
area(WA ).
6.What are the different types of aperture.?
Prepared by : LENIN RAJA, Assistant Professor / Research Coordinator,
Sri Vidya College of Engineering & Technology, Virudhunagar, Tamilnadu.
Mail to: leninaucbe@gmail.com; lenin.svcet@gmail.com
7.Define different types of aperture.?
Effective aperture(Ae).
It is the area over which the power is
extrated from the incident wave and delivered to the
load is called effective aperture.
Scattering aperture(As.)
It is the ratio of the reradiated power to
the power density of the incident wave.
Loss aperture. (Ae).
It is the area of the antenna which
dissipates power as heat.
Collecting aperture. (Ae).
It is the addition of above three
Prepared by : LENIN RAJA, Assistant Professor / Research Coordinator,
Sri Vidya College of Engineering & Technology, Virudhunagar, Tamilnadu.
Mail to: leninaucbe@gmail.com; lenin.svcet@gmail.com
, apertures.
Physical aperture. (Ap).
This aperture is a measure of the
physical size of the antenna.
8. Define Aperture efficiency?
The ratio of the effective aperture to
the physical aperture is the aperture efficiency. i.e
Aperture efficiency = hap = Ae / Ap
(dimensionless).
9. What is meant by effective height?
The effective height h of an antenna is the
parameter related to the aperture.It may be defined as
the ratio of the induced voltage to the incident field.i.e
H= V / E.
10. What are the field zone?
The fields around an antenna ay be divided into
two principal regions.
i. Near field zone (Fresnel zone)
Prepared by : LENIN RAJA, Assistant Professor / Research Coordinator,
Sri Vidya College of Engineering & Technology, Virudhunagar, Tamilnadu.
Mail to: leninaucbe@gmail.com; lenin.svcet@gmail.com
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