2. WHY…….????
Directionality:
◦ Omni (360º coverage) directional
◦ Directional (limited range of coverage)
Compatibility
Should not require any alignment during the
fixation.
Light weight
Easy implementation
Low power consumption
Low cost
Easily replaceable
Gain:
Gain should be more.
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3. ODA:
An Omni-Directional Antenna(ODA) is an
antenna which radiates radio wave power
uniformly in all directions in one plane, with
the radiated power decreasing with
elevation angle above or below the plane,
dropping to zero on the antenna's axis.
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5. Contd….,
In this case, along the z-axis, which would correspond to
the radiation directly overhead the antenna, there is very
little power transmitted. In the x-y plane (perpendicular to
the z-axis), the radiation is maximum.
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6. (ii)Gain:
Antenna gain is a measure for antennas efficiency.
Gain is the ratio of the maximum radiation in a
given direction to that of a reference antenna for
equal input power.
Generally the reference antenna is an isotropic
antenna.
Gain is measured generally in “decibels above
isotropic (dBi)” or “decibels above a dipole (dBd).
dBi = dBd + 2.15
**(Gain is mainly depends on the mechanical size
of an antenna)**
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9. Used in,
Mobile phones
Wi-fi modem’s
Walkie-Takie’s
Cars-(FM antenna)
Wireless Microphones(Mike) etc…,
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10. Limitations:
Although their gain should be very high, due
to some external factors i.e..,(interference,
fading etc..,) their gain should get decreased.
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