patch antenna presentation (1)

8/4/2019 Patch Antenna Presentation (1)

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… • Designing hardware is a complex

phenomenon. Especially when we talk about antennas.

• We cant just make any hardware with

out studying its behavior or characteristics.

• HFSS® from Ansoft corp. provides thatplatform, where we can design the

prototype,and then study its behavior and observe its characteristics andthen keeping them in mind fabricateour hardware.

1



I nt

r o d u ct

i ont oH F S

S ®

• The acronym stands for “High

Frequency Structural Simulator”.

• It is one of the most popular andpowerful applications used for

antenna design, and the design ofcomplex RF electronic circuits in theindustry.

• Major users of this software for rndpurposes are Ericsson ,Nokia etc.

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3



As we know the lengthof a half-wave dipoleantenna should behalf the wavelength ofthe operating carrier wave frequency. Thus

the dipole modeled inHFSS® has thefollowingspecifications

Center frequency 200 MHz

Wavelength „λ‟ 1.5m

λ/2 0.75m

Length of eacharm

0.375m

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Radiation Pattern

• The computed

radiation pattern of themodeled dipoleantenna is as follows.

3-D Radiation Pattern

• 3-Dimensional patternof the radiation is asfollows

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The E-fields determines the type of polarization . The electric andmagnetic fields of the modeled dipole antenna are shown.

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• A Microstrip Patch Antenna consists of ametallic strip or a patch mounted on a

dielectric layer (substrate) supported byground plane.

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• The micro strip patch is designed so itspattern maximum is normal to the patch

hence making it a broadside radiator.

• The conducting micro strip or patch and theground plane are separated by a substrate.

• There are numerous substrates that can beused for the design of micro strip antennasand their dielectric constants are usually in

the range of (2.2 to 12).

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• There are many configurations that can beused to feed microstrip antennas.

• There are three most common structuresthat are used to feed planar printedantennas

• Feeding techniques are given below.

• Coaxial probe feeds

• Microstrip line feeds

• Aperture coupled feeds

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12



•The Coaxial feed or probe feed isa very common technique used for feeding Microstrip patch antennas.

•The inner conductor of the coaxialconnector extends through thedielectric and is soldered to theradiating patch, while the outer conductor is connected to theground plane

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• For the modeling of Micro Strip Patchantenna, a paper of IEEE was kept as a

reference paper.

• Application of Three-Dimensional Finite-

Difference Time Domain Method of theAnalysis of Planar Micro strip Circuits byDavid M.Sheen ,Sami M.Ali, Jin AU. Kongwas repulbished.

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Substrate used Duroid

Dielectricconstantgiven

2.2

Thickness ofthe Substrate

0.794 mm

Length of thePatch

12.45mm

Width of thePatch

16.0 mm

Strip line feed 2.09mm awayfrom the leftcorner.

•The antenna mentionedin the IEEE papers followsa strip line feed.

•The dimensions used for the antenna centers it at7.8 GHz.

•Following table showsthe entire data about theMicro Strip Patch antenna.

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• Microstrip Antennamodeled on HFSS®

• Microstrip Antennagiven in the IEEE paper

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• Return loss graph of our modeled antennawas compared to that of the one given in

the IEEE paper.

• The main purpose of this comparison was toauthenticate the behavior of the return loss

graph given in the IEEE paper and that ofthe modeling software which is HFSS ®.

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RESULTS GENERATED BYHFSS®

RESULTS GIVEN IN IEEE PAPER

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• The results clearly showed that the behavior

of the return loss graphs of both theantennas are almost similar.

• Now after gaining confidence on the patchdesign we moved forward to our next partof the project that was to model and thenfabricate a prob feed Patch Antenna

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21



• Mathematical calculations werecarried out for the dimensions of our

Prob Feed Patch Antenna, atfrequency of 1.8GHz.

• Calculations, carried out for thePatch are as under.

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• The width of the Microstrip patchantenna is given by

• Substituting c = 3x108 m/s

• ε r = 4.4

• f o = 1.8 GHz

• We calculated the width and it came

out to be

W=50.77mm

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• The formula for calculating the Effectivedielectric constant is

• Substituting ε r = 4.4, W = 50.77 mm and

h = 1.6 mm we get:

• We get the effective dielectric constant as

εreff =4.14

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• The formula for the Effective length is givenas

• Substituting the mentioned values as

• ε reff = 8.79• c = 3e8 m/s

• f o = 1.8 GHz we get

Leff =40.9mm

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• The formula for the length extension isgiven as

• Substituting values in the formula.

• The value for length extension comes outto be

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• The actual length of the patch can nowbe calculated via the following

• Substituting the values in the above

formula as• Leff = 24 mm

• ΔL = 7.5 e-4 mm we get

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• As mentioned earlier that the results are thesame if the size of ground plane is greater

than the patch dimensions byapproximately six times the substratethickness all around the periphery. For alarger element size we took the groundplane approximately twelve times the

substrate thickness

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Geometry of Probe fedPatch Antenna

Tabular form of ourCalculations

CENTER

FREQUENCY

1800 MHz

SUBSTRATEUSED

G10 FIBERGLASS (FR4)

DIELECTRIC

CONSTANT

4.4

LENGTH 40.1mm

WIDTH 50.77mm

HEIGHT 1.6mm

FEEDINGMETHOD

COAXIALFEED

POLARIZATION LINEAR.

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30



R et ur nl o

s s

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32

7dB



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•The VSWR of themodeled antennacomes out to be

very good.

•The VSWR of anypractical antennashould be atleast

or less than 2.

•The VSWR of our antenna came outto be 1.25 at aresonantfrequency if 1.76GHz

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35

MinimumReturn Loss will

decide thecoordinates offeed point

Finding the Ideal Feed

Point Location

(x,y)



( 0,-1 )

36

( 0,0 )



(0,-2)

(0,-3)

37

( 0,-2 )

( 0,-3 )



-4

-5

38

( 0,-4 )

( 0,-5 )



-6

-7

39

( 0,-6 )

( 0,-7 )



-8

-9

40

( 0,-9 )

( 0,-8 )



( 0 , -11 )

41

( 0,-11 )



42

S.No Feed location(x,y)

Centerfrequency(GHz)

Return loss(dB)

1 (0,0) 1.76 -0.07 2 (0,-1) 1.76 -0.33 3 (0,-2) 1.76 -0.75 4 (0,-3) 1.76 -1.89 5 (0,-4) 1.76 -2.02 6 (0,-5) 1.76 -4.98 7 (0,-6) 1.76 -7.34 8 (0,-7) 1.76 -9.55 9

(0,-8) 1.76 -14 10 (0,-9) 1.76 -19.79 11 (0,-10) 1.76 -21.45 12 (0,-11) 1.76 -24.83



F a

b r i c at i onP r o

c

e d ur e

•After the modeling of the probe feed patch antenna andachieving satisfactory results we came to our fabricationpart.

•For this purpose we etched two antennas. To learn howpatch antennas are built we constructed one antennaourselves

•In order to get more accurate results we got one antennaetched from Allied electronics Lahore.

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44



F i n

al

s t e pt ow

ar d

s t h

ef a

b r i c at i on

45



N et w or

k An

al

yz er

•A network analyzer is an instrument usedto analyze theproperties of

electrical networks,especially thosepropertiesassociated with thereflection andtransmission ofelectrical signalsknown as scatteringparameters

(S-parameters).

•Network analyzersare used mostly athigh frequencies

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R et ur nL o

s s o

f t h eAn

t enn

a

The following figure was obtained from the vector network analyzer.

The figure shows the return loss graph of the patchantenna we fabricated. The results came out to be

outstanding. Well beyond our expectations. The return lossgraph showed that the return loss at 1.82 GHz is -30.261 dB

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Th f ll i fi h th V lt t di



V ol t

a g e S t an

d i n

gW

av

eR

at i o

( V

S WR

)

•The following figure shows the Voltage standingwave ratio of our patch antenna.

•The VSWR of any working antenna should notexceed 2.

•In our case the result came out to be veryoutstanding. At the resonant frequency of 1.82GHzthe VSWR comes out to be 1.0840.

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B A

CK

V I E W ( GR

O U N

D P L ANE

) OF

P AT CH

ANT E NNA

49



F R

ONT

V I E W ( P AT CH

) OF P AT CH A

NT E NNA

50



As we progressed with the passage of time we had to facechallenges in different ways. If they wouldn‟t have been solved

timely we could not have achieved our goal. A brief review ofdifficulties during the whole project are summarized below.

• Unavailability of HFSS® • Very few people having knowledge of soft ware, so findingan instructor of this field was difficult and time consuming.

• Lack of antenna testing equipment in any of theeducational institutes.

• People who had knowledge of network analyzer atcomsats were busy with there own university commitments so

taking some time from them also became an isssue.

•This problem was solved after requesting to Dr.Shahid A.KhanDean comsats who requested the concerned person to helpus.

patch antenna presentation (1)

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