April 10, 2023

Presented by;Sanket S. Yavalkar

P.G. Student (EXTC) (Enrollment No.138)Sardar Patel Institute of Technology,

Mumbai

Under Guidance ofDr.S.S.Rathod

Water Salinity Measurement System Using Microwaves

Project Seminar on

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April 10, 2023

Contents

2

Aim and ObjectivesProject MotivationLiterature SurveyWater Salinity System IntroductionNeed of WorkAntennasDesign of Patch AntennaParametric Study of Patch AntennaSalinity and Various Salinity Measurement

SystemsMicrowaves Based Water Salinity

Measurement SystemProposed SystemConclusion

AimTo design the patch antenna to use it for

Salinity Measurement System

ObjectiveTo study antennas.Study Salinity Measurement Systems.Study and Design a Patch Antenna.Use that antenna for Measuring Salinity of

Water.

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April 10, 2023

Project Motivation

4

Actual Photograph of Bore-well of water

Water to be Tested

April 10, 2023

Literature Survey

5

Patch AntennasJames Maxwell and Ruolph Hertz are the one

who described the electromagnetic waves in 18th century [1-2].

Antennas are the one which are first studied and developed by Guglielmo Marconi in the first few years of 20th century [3].

In year 1979, the microstrip patch antennas were proposed by, Munson R. with Joy E., in which they proposed the planer end-fire antennas [4].

The present technology of printed antennas points to use of available structures and designs.

April 10, 2023

Literature Survey

6

Salinity Measurement System First published work was by famous chemist Robert

Boyle in 17th century about “Observations and Experiments on Saltiness of Sea Water,” cleared up some ideas about salt.

In 18th century, Mist chemists Hitherto had evaporated the water to find out salt contents.

Between 1843 and 1865 the Danish chemist, J.G.Forchhammer published several milestone papers on the compostion of sea water. His techniques were gravimetric; he did not use the evaporation method. He used data from all over the world, and compared his results for these different waters. Forchhammer introduced the word ‘Salinity’.

April 10, 20237

In the years 1873-1876 H.M.S. Challenger sailed almost 69,000 miles about the world making oceanography observations. Seventy-seven salinity samples were collected from various depths. They were analysed by W.Dittmar, in “the most extensive sea water analysis performed before, or since.”

The concepts noted above were generally accepted by the late 19th century but the man behind the coefficients of chlorine and specific gravity were uncertain.

Chlorine content of the samples was determined by titration using the Mohr method by the Swedish chemist, S. P. L. Sorensen in 1901. The equation relating salinity and chlorinity (S=1.805CL+0.030) was stated by him from his observations.

April 10, 20238

Knudsen determined the specific weights of the samples. C. Forch determined the volume expansion of sea water. In a remarkably short time the results of these studies were published in the famous "Hydrographical Tables", of 1901 relating chlorinity, salinity and density of sea water. These tables have been in use for seventy years

Since 1955 salinity determination by measuring the electrical conductivity of sea water has come into prominence until at present many more determinations of salinity are made by the conductivity measurements than by chemical titrations.

The latest instruments are almost as sensitive as the best laboratory salinometers but because of the operating environment are rated by the manufacturer as giving an accuracy of about 0.01‰ in salinity. [5]

Water Salinity MeasurementSalinity

Practical Salinity is defined on Practical Salinity Scale (PSS) of 1979 (UNESCO (1981, 1983)) in terms of the conductivity ratio which is the electrical conductivity of the sample at temperature =C and pressure equal to one standard atmosphere (P=0 dbar and absolute pressure P equal to 101 325 Pa), divided by the conductivity of a standard potassium chloride (KCL) solution at the same temperature and pressure. [6]

When =1, the Practical Salinity is by definition 35.

is a constant.

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April 10, 2023

Need of Work

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Effect of use of salty waterAgriculture

Agriculture is not possible on saline Land.

SocietyQuality of ConstructionDams Construction

Healthkidney diseasekidney stoneshigh blood pressure

Saline Land(Courtesy : Google Image)

Use of Saline Water for Construction( Courtesy : Google Image )

April 10, 2023

Salinity Measurement Systems

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Chemical Method of Salinity MeasurementThe concentration of many major dissolved

constituents of one or more major constituents can be used to deduce the total salinity, S. Eg. Chlorine

Physical Methods of Salinity MeasurementsPure water is a poor conductor of electricity. However,

the presence of ions in water enables it to carry an electric current.

AC current is used to measure conductivity.Conductivity is related with salinity.

April 10, 2023

Microwave Based Salinity Measurement System

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Electromagnetic Waves Propagation through Conducting Medium

=skin depth=permibility = 2πf where f is frequency of operation= Conductivity (S/m)

Antenna???

Click icon to add picture

Antenna is transducers (it converts one from of energy in to another) that transmit or receive electromagnetic waves (has electric and magnetic field component which oscillate in phase perpendicular to each other and to the direction of energy propagation).

Comparison Of Different Antenna

Radiation

Patterns

Power Gain Polarization

Dipole Broadside Low Low Linear

Multi Element

Dipole

Broadside Low/medium Low Linear

Flat Panel

antenna

Broadside Medium Medium/high Linear/circular

Parabolic Dish

Antenna

Broadside High High Linear/circular

Yagi Antenna Endfire Medium/high Medium/high Linear

Slotted Antenna Broadside Low/medium Low/medium Linear

Microstrip

antenna

Endfire Medium Medium Linear/circular

Basic form of Patch Antenna

Design of Patch AntennaSystem Requirements

The frequency operation must be less i.e. in MHz

Size of antenna must be as small as possible

Transmission Losses must be less

ISM band : 0.9 GHz, 2.45GHz, 5.81GHzSo if we select 0.9 GHz then size increase and if we select 2.45 GHz then skin depth decreases. For experimentation purpose 1.57GHz is chosen.FR4 (= 4.47) with loss tangent 0.02 is taken as substrate.

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April 10, 2023

Transmission Line Model

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1. Calculation of the Width (W) : = 57 mm

2. Calculation of Effective dielectric constant ():

=

3. Calculation of the Effective length ( ):=

April 10, 202318

4. Calculation of the length extension ():=

5. Calculation of the actual length (): = 47.77 mm

6. Calculations of finite plane dimensions ():

6(1.56) + 47.77= 57.13 mm=6(1.56) + 57 = 114.13 mm

Design of Patch Antenna

Antenna Specifications

 

  

 

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Parameters

Length 55.5 mm

Width 45 mm

Ground Plane Length 110 mm

Ground Plane Width 90 mm

Height 1.56 mm

Substrate FR4

Dielectric Constant 4.47

Loss Tangent 0.02

Resonance Frequency

1.57 GHz

April 10, 2023

Parametric Study of Patch Antenna

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Effect of Height Effect of WidthEffect of Dielectric ConstantEffect of Loss TangentEffect of Feed Location

Effect of Height

Frequency (GHz)

1.48 1.50 1.52 1.54 1.56 1.58 1.60 1.62

Return L

oss (dB)

-20

-18

-16

-14

-12

-10

-8

-6

-4

-2

0

Height = 3 mmHeight = 1.5 mm

Discussion : With an increase in h from 1.5 mm to 3 mm, the following effects are observed:

• Resonance frequency decreases• The BW of the antenna increases• BW is directly proportional to height(h)

Effect of Width

Frequency (GHz)

1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1

Return L

oss (d

B)

-18

-16

-14

-12

-10

-8

-6

-4

-2

0

Width = 44.5Width = 43.5

Discussion : With an increase in W from 43.5 mm to 44.5 mm, the following effects are observed:

• Resonance frequency decreases from 1.64 GHz to 1.57 GHz

• BW of the antenna increases

Effect of Dielectric Constant

Frequency (GHz)

1.48 1.50 1.52 1.54 1.56 1.58 1.60 1.62

Re

turn Lo

ss (dB

) -18

-16

-14

-12

-10

-8

-6

-4

-2

0

r =1r =2.2r =4.4

Discussion: Єr is decreased to 1, the resonance frequency increases. A better

comparison of effect of Єr is obtained when the antenna is designed to operate in the same frequency range for different values of Єr .

April 10, 202324

Frequency (GHz)

1.48 1.50 1.52 1.54 1.56 1.58 1.60 1.62

Retu

rn L

oss (d

B)

-35

-30

-25

-20

-15

-10

-5

0

tan = 0.02

tan = 0.001

Effect of Loss Tangent

Discussion: It is observed that lesser the loss tangent the less the loss in the

probe.

Effect of Feed Location

Frequency (GHz)

1.560 1.565 1.570 1.575 1.580

Ret

urn

Loss

(d

B)

-18

-16

-14

-12

-10

-8

-6

-4

-2

0

feed at (10,6)feed at (10,12)feed (10,7)feed (10,8)feed (10,9)feed (10,10)

• The feed point at (10,8)giving most negative RL

Conclusion From Parametric Study of Above Design of Antenna

Change In

Parameters

Resonance Frequency

Bandwidth

Feed Location

No shift No Chage

Height Increases IncreasesWidth Decreases Decreases

εr Decreases DecreasesLoss

TangentIncreases Decreases

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Manufactured Antenna

Parameters

Length 55.5 mm

Width 45 mm

Ground Plane Length 110 mm

Ground Plane Width 90 mm

Height 1.56 mm

Substrate FR4

Dielectric Constant 4.47

Loss Tangent 0.02

Resonance Frequency

1.57 GHz

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Measured Results

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 ResultsMeasured Results

Frequency (GHz)

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  Simulated Results

Measured Results

Error

Resonance

Frequency

1.5710GHz 1.5760GHz +5MHz

Bandwidth

1.11% 1.27% -0.16%

Salinity and Unit to Measure Salinity

The term salinity refers to the concentration of ions in water.

Salinity is measured as a concentration of grams of salt per kilogram of water (g/Kg)

This quantity is usually expressed as the measure of salt per thousand parts of seawater (ppt or )

The method determines the practical salinity (PS) of seawater samples which is based on electrical conductivity measurements.

PSS defines the practical salinity of seawater in terms of the conductivity ratio () of the conductivity of the sample at

a temperature of and pressure of one standard atm.to that of a potassium chloride (KCl) solution containing 32.4356g of Cl in a mass of 1Kg of solution.[7]

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Salinity Measurement Methods

1. Gravimetric Determination

1. Take a known amount of salty water.2. Evaporate it to dryness3. Weigh the remaining salts

Limitations :

4. Residue left after evaporation is a complex mixture of salts together with some water of hydration bound to the solids, plus a small amount of organic material

5. So produces unreliable results

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Salinity Measurement Methods

2. Chemical Method

1. The concentration of many major dissolved constituents of one or more major constituents can be used to deduce the total salinity, S.

2. Easiest constituents to measure are the halides i.e chloride, bromide and iodide

3. Cl is the chlorinity of the sample, defined as the concentration of chloride in seawater (in parts per thousand) assuming that the bromide and iodide have been replaced by chloride.

4. Chlorinity is measured by titration31

Salinity Measurement Methods

3. Physical Method1. Electrical conductivity of sea water is

proportional to its salinity2. Conductivity is inversely proportional to resistance3.4. As the values of all the resistances,except R2, are known, the resistance of the seawater sample can be calculated.

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Use of Microwaves for salinity MeasurementMicrowaves are one form of Electromagnetic

Waves (EMW).When microwaves are allow to pass through

water they have tendency to degrades completely after some distance inside the water. The distance is called as skin depth ()

Where is conductivity of water = 2Πfi.e. skin depth is inversely proportional to frequency and conductivity of material.

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Use of Microwaves for salinity MeasurementSalt is composed of sodium chloride (NaCl)Pure water is poor conductor of electricity.But the ions of NaCl with water increases

conductivity of water.So skin depth decreases as salt percentage in water

increases.EM waves totally degrade after a distance equal to

skin depthOne can measure attenuation of EM waves using

various instruments like network analyser, spectrum analyser, etc.

We can build up a relation in attenuation of EM waves with percentage salt content in water.

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Methodology

35

 

     

 

 

 

Transmitting Antenna

Receiving Antenna

Sample Holder/Cavity

Water Samples

Firmware/Software

Signal Generator

Spectrum Analyser

Analog Input File

Procedure :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.36

Apparatus Required

Transmitting Antenna and Receiving Antenna

Spectrum AnalyserSignal GeneratorSample Holder

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Experimental Setup

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Results and DiscussionSample % of

salt in

water

Atten-

uation

(dBm)

Without Water

  -10.35

Sample 1 0 -30.04

Sample 2 2.5 -34.86

Sample 3 5 -35.98

Sample 4 7.5 -38.24

Sample 5 10 -44.23

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Proposed Indigenous offline Water Salinity System

1.57 GHz Oscillator

Power Amplifier

Isolator

Patch AntennaTx

Patch Antenna

Rx

LNA BPF 1.57GHz

MixerBPF

70MHz

IF Amplifier Coupler A1

1

Ampl. Detector

DC Ampl.

Computer

1.50 GHz Oscillator

Sample Holder/Cavity

Data Acquisition Unit

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Firmware

(a) Operational Mode

(b) Calibration Mode

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April 10, 2023

Applications

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1. Salinity Measurement 2. Impurity of Water Measurement3. Soil Moisture Measurement4. Grains Moisture Measurement

ConclusionPatch antenna is studied and designed.Analytical Study of Patch Antenna.Parametric study of patch antenna.Various Salinity Measurement System are

studied.Implementation of Microwave based Offline

Salinity Measurement System using Patch antennas.

Offline Salinity Measurement System is proposed.

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Future WorkA better calibration scheme will make the

system better.The use system can be further expanded

by using it not only for salt measurement but also impurity measurement in water.

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April 10, 2023

Publications

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1. S.S.Yavalkar, R.T.Dahatonde, S.S.Rathod, S.B.Deosarkar, “Comparative Analysis of Bandwidth Enhancement of Microstrip Patch Antenna using Various Geometries,” IOSR Journal,Vol.3, Issue 4, pp.Sep.2012

2. S.S.Yavalkar, R.T.Dahatonde, S.S.Rathod, S.B.Deosarkar, “Parametric Study of Rectanguar Microstrip Antenna,” IOSR Journal,Vol.5, Issue 2,pp.49-53,Apr. 2013.

3. S.S.Yavalkar, R.T.Dahatonde, S.S.Rathod, “Water Salinity Measurement Using Patch Antennas,” INDICON-2013, Mumbai, (communicated)

April 10, 2023

References[1] Maxwell James Clerk, “A dynamic Theory of Electromagnetic

Field,” Philosophical Transaction of the Royal Society of London,1865.

[2] Heinrich Hertz, “Electric Waves: Being Researches on the Propagation of Electric Action with Finite Velocity Through Space,” Dover Publications, 1893.

[3] Bondyopadhyay,K. Prebir, "Guglielmo Marconi – The father of long distance radio communication – An engineer's tribute,"25th European Microwave Conference,pp.879, 1995.

[4] Munson, R. Joy, E., “Microstrip antenna technology at ball aerospace systems, Boulder, Colorado,” Antennas and Propagation IEEE society newsletter, Vol.21 pp.4 - 6, June 1979.

[5] E.R.Walkar, Salinity in Physical Oceanography, Pacific Marine Science Report,Institute of Ocean Science,Victoria B.C., pp.21-76, Sept. 1976.

[6] Practical Salinity Scale, Unesco,1979[7] Ghassemi F., Jakeman A.J., Nix H.A., Stalinisation of land and

water resources: Human causes, extent, management and case studies, UNSW Press, Sydney, Australia, and CAB46

Thank You !!!

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April 10, 202348

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April 10, 2023

Effect of Feed Location

Frequency (GHz)

1.560 1.565 1.570 1.575 1.580

Ret

urn

Loss

(d

B)

-18

-16

-14

-12

-10

-8

-6

-4

-2

0

feed at (10,6)feed at (10,12)feed (10,7)feed (10,8)feed (10,9)feed (10,10)

• Minimum Return Loss (RL) occurs at feed-location (10,8). •There is only one feed point where RL is minimum.

Discussion :

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April 10, 2023

Effect of height

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 = 3 mmHeight = 1.5 mm

Discussion : With an increase in h from 1.5 mm to 3 mm, the following effects are observed:

• Resonance frequency decreases• The BW of the antenna increases• BW is directly proportional to height(h)51

April 10, 2023

Effect of Dielectric Constant

Frequency (GHz)

1.48 1.50 1.52 1.54 1.56 1.58 1.60 1.62

Re

turn

Lo

ss (

dB

)

-18

-16

-14

-12

-10

-8

-6

-4

-2

0

r =1r =2.2r =4.4

Discussion: Єr is decreased to 1, the resonance frequency increases. A better

comparison of effect of Єr is obtained when the antenna is designed to operate in the same frequency range for different values of Єr .

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April 10, 2023

Effect of Width

Discussion:• The resonance frequency decreases from 1.64 GHz to 1.57 GHz due to

the increase in ∆L and Єe.• The BW of the antenna increases; however, it is not very evident from

these plots, because the feed point is not optimum for the different widths53

April 10, 2023

Effect of Shape

Parameters RMSA L-Shape S-Shape

Geometry

Return Loss -20 dB -15 dB -30dB

Bandwidth 30MHz 35MHz 40 MHz

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April 10, 2023

Effect of Shapes

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April 10, 2023

Fractal Antenna Design

1. Iteration 1

2. Iteration 2

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3. Iteration 3

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April 10, 2023

Plan of Work

Current Work Till now different BW enhancement methods were studied and implemented. The methodstill studied are : 1. Use of thicker substrate or use of stacked patches.2. Use of slots. 3. Fractal design of patch.

Remaining Work There are still some more methods to be studied for enhance the BW. These are like : 1. Suspended design of fractal. 2. Monopole patch antenna.

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April 10, 2023

Thank You !!!

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April 10, 2023

Analysis of RMSA using Transmission line Model

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