Post on 10-Sep-2015
description
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Fig.2.1.Radiation From Antenna
Antenna Transmission
Line
Antenna Free Space Wave Antenna Transmission
Line
Antenna Free Space Wave Antenna Transmission
Line
Antenna Free Space Wave Antenna Transmission
Line
Antenna Free Space Wave Antenna Transmission
Line
Antenna Free Space Wave
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D
Far-Field
Radiating
Near Field Reactive
Near Field
Near
Field Far Field
Fraunhofer
D
Antenna
Fresnel
Near
Field Far
Field
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Ground Plane
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L C
Substrate
Patch
Ground Plane Co-axial Feed
L
R L C
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L
R L C
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Aperture/Slot
Microstrip Line
Patch
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Microstrip
Line
Patch
Substrate 2
Substrate 1
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C
BG
BG
[
]
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[( )(
)
( )(
)
]
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So it was
obvious question
arise in early
mans mind
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Lv
Wp
Wf
Y
X
( )
( )
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( )
( )
( )
( )
( )
( )
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|
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(
)
(
)
(
) (
)
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[
]
( )
( )
( )
{
| |
| | | |
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[ (
) ( )]
{ [ (
) ( )]
[ ( ) (
)] }
[
( )
( )
]
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[
]
Feed
Patch
Finite
Ground
(0,0)
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[( )(
)
( )(
)
]
40
mm
mm
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Frequency (GHz)
1.5 1.51 1.52 1.53 1.54 1.55 1.56 1.57 1.58 1.59 1.6
Ret
urn
Los
s (d
B)
-18
-16
-14
-12
-10
-8
-6
-4
-2
0
feed (10,7)
feed (10,8)
feed (10,9)
feed (10,10)
feed (10,12)
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Frequency (GHz)
1.48 1.50 1.52 1.54 1.56 1.58 1.60 1.62
Ret
urn
Los
s (d
B)
-20
-18
-16
-14
-12
-10
-8
-6
-4
-2
0
Height = 1.5 mm
Height = 3 mm
Frequency (GHz)
1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1
Ret
urn
Los
s (d
B)
-18
-16
-14
-12
-10
-8
-6
-4
-2
0
Width = 44.5
Width = 43.5
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Frequency (GHz)
1.48 1.50 1.52 1.54 1.56 1.58 1.60 1.62
Retu
rn L
oss (
dB
)
-18
-16
-14
-12
-10
-8
-6
-4
-2
0
r=1
r=2.2
r=4.47
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Frequency (GHz)
1.48 1.50 1.52 1.54 1.56 1.58 1.60 1.62
Retu
rn L
oss
(dB
)
-35
-30
-25
-20
-15
-10
-5
0
tan = 0.01
tan = 0.001
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( )
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Thermostat
Stan
dard
Seaw
ater
R1
R3V
ariable
Resistance
Fixe
d
Res
ista
nce
Unknow
n
Seawater
R2
R4
Supply
G
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]
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{| |
}
{| |
}
(
(
))
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{| |
} | |
(| |
)
{
[
]}
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(| | (
))
(| | (
))
( )
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Take pure form of water or take
water whose contents are known
Take a patch antenna having cavity above its
conducting patch. Use as a receiver.
Use another antenna without cavity as a
transmitting antenna
Measure the
attenuation with
air in cavity.
Store Result
for Reference.
Pour the Pure form of water in the cavity
Measure the
attenuation
Store Result
for Reference
Pour known quantity of salt (sample 1..n )in
pure water
Measure as many samples as one can to have
many references for calibration.
Use calibrated data as a reference during
actual measuring of salinity at field.
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Transmitting
Antenna
Receiving
Antenna
Sample
Holder/Cavity
Water
Samples
Firmware/
Software
Signal
Generator
Spectrum
Analyser
Analog
Input File
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Frequency (GHz)
1.555 1.560 1.565 1.570 1.575 1.580 1.585
Re
turn
Lo
ss (
dB
)
-50
-40
-30
-20
-10
0
Simulated Results
Measured Results
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% of Salt in per 10 g of Sample
0 2 4 6 8 10 12
Atte
nua
tio
n (
dB
m)
-45
-40
-35
-30
Attenuation Curve
1.57 GHz
Oscillator
Power
Amplifier
Isolator
Patch Antenna
Tx
Patch
Antenna
Rx
LNA BPF
1.57GHz
MixerBPF
70MHz
IF
Amplifier
Coupler
A11
Ampl.
Detector
DC
Ampl.
Computer
1.50 GHz
Oscillator
A11
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(b) Calibration Mode
(a) Operational Mode
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