i

ii

iii

iv

v

vi

vii

viii

ix

x

1

W

L

2

3

4

5

6

7

8

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

9

10

11

12

13

| |

| |

| |

14

15

16

17

D

Far-Field

Radiating

Near Field Reactive

Near Field

Near

Field Far Field

Fraunhofer

D

Antenna

Fresnel

Near

Field Far

Field

18

19

20

Ground Plane

21

L C

Substrate

Patch

Ground Plane Co-axial Feed

L

R L C

22

L

R L C

23

Aperture/Slot

Microstrip Line

Patch

24

Microstrip

Line

Patch

Substrate 2

Substrate 1

25

26

27

C

BG

BG

[

]

28

[( )(

)

( )(

)

]

29

| |

30

31

So it was

obvious question

arise in early

mans mind

32

Lv

Wp

Wf

Y

X

( )

( )

33

( )

( )

( )

( )

( )

( )

|

|

| |

|

|

34

|

|

(

)

(

)

(

) (

)

35

[

]

( )

( )

( )

{

| |

| | | |

36

[ (

) ( )]

{ [ (

) ( )]

[ ( ) (

)] }

[

( )

( )

]

37

38

[

]

Feed

Patch

Finite

Ground

(0,0)

39

[( )(

)

( )(

)

]

40

mm

mm

41

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)

42

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

43

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

44

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

45

46

( )

47

48

49

50

51

52

53

Thermostat

Stan

dard

Seaw

ater

R1

R3V

ariable

Resistance

Fixe

d

Res

ista

nce

Unknow

n

Seawater

R2

R4

Supply

G

54

55

56

57

[

]

58

59

{| |

}

{| |

}

(

(

))

60

{| |

} | |

(| |

)

{

[

]}

61

(| | (

))

(| | (

))

( )

62

63

64

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.

65

Transmitting

Antenna

Receiving

Antenna

Sample

Holder/Cavity

Water

Samples

Firmware/

Software

Signal

Generator

Spectrum

Analyser

Analog

Input File

66

67

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

68

69

70

71

% 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

72

73

74

(b) Calibration Mode

(a) Operational Mode

75

76

77

78

79

80

81

82