Post on 03-Jun-2018
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Basics of Antenna
Shunmugapriyan.MII Year M.E(Communication Systems)
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Outline
Antenna
Antenna Classification
Antenna Characteristics
RF tools
Antenna Design
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Antenna
An antenna is an electrical device which
converts electrical power into radio waves, and
vice versa.
The antenna radiates the energy from the
current electromagnetic waves(radio waves).
In reception an antenna converts
electromagnetic wave into a tiny voltage at its
terminals, that is applied to a amplifier.
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Wave Propagation in Antenna
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Antenna Classifications
Omni Directional
Monopole/Whip
Dipole
Loop
Whip
PIFA( Planar Inverted-F antenna) Bi-Conical
Directional Patch
YagiUda
Horn Helical
Parabolic
Log Periodic
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Characteristics of Antenna
Resonance Frequency
Return Loss
VSWR
Radiation Pattern
Directivity
Bandwidth
Beam Width
SAR-Specific Absorption Rate
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Resonance FrequencyFrequencies at which the response amplitude is
a relative maximum are known as the system's
resonant frequencies.
Resonance occurs when a system is able to
store and easily transfer energy between two
or more different storage modes.
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Return LossReturn loss is ratio between incident power
and reflected power.
= 10
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VSWR
VSWR=
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Relation between VSWR, Reflection
Coefficient and Return lossVSWR Refection
Coefficient()
Reflected
Power(%)
Reflected
Power(dB)
1 0.000 0.000 -infinity
1.5 0.200 4 -14
2 0.333 11.1 -9.55
2.5 0.429 18.4 -7.36
3 0.5 25 -6
6 0.714 51 -2.92
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Radiation Pattern
Graphical representation of received power by
an antenna.
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Directivity
antenna radiates in the direction of its strongest
emission, versus the power density radiated by
an ideal isotropic radiator.
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Bandwidth
Bandwidth is difference between upper cut off
frequency and lower cut off frequency.
Bandwidth(Hz)=
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SAR
Specific absorption rate (SAR) is a measure
of the rate at which energy is absorbed by the
body when exposed to a radio frequency (RF)
electromagnetic field.
It can also refer to absorption of other forms of
energy by tissue, including ultrasound.
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Mobile Phone SAR
Brand SAR(W/Kg)
SAMSUNG 0.29-0.96
NOKIA 0.8-1.3
SONY ERICSSON 1.22-1.56
MOTOROLA 0.45-1.52
LG 0.35-1.52
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RF Tools
2D Tools
Agilent Advanced Design System (ADS)
Empire Xccel
3D Tools HFSS
CST Studio Suite
IE3D
COMSOL
FEKO
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Antenna Design
Dielectric constant(FR4=4.4-4.6)
Substrate Height(1.6mm)
Application
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Return Loss
Return loss is -22.71dB
at the Resonance
frequency of 2.4GHz
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VSWR
VSWR is 1.16 at the
Resonance frequency
of 2.4GHz
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Radiation Pattern
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