Antena Dipole telkom

7/25/2019 Antena Dipole telkom

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ANTENA DIPOLE


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ANTENA DIPOLE

Antena dipole dalam beberapa aspek miripdengan saluran transmisi yang open circuit.

Antena yang termasuk tertua, paling

sederhana, paling murah dan banyak

aplikasinya.

ANTENA DIPOLE


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Macam-macam antena Dipole

Ada beberapa macam antena dipole yaitu :

Half wave Dipole

hort Dipole Antenna Antena !iconical

"ylindrical Antenna

!ow #ie Antenna $olded Dipole Antena

Antena Monopole

Antena %oop


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Dipole & 'elombang

Half-wave

Dipole

a. "urrentdistribution

b. (adiation

pattern


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Dipole & 'elombang )samb*

Distribusi arus pada antena dipole + gelombang yang

tipis dapat didekati dengan gelombang berdiri sinus

dengan arus.


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Dipole & 'elombang )samb*


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E feld Lines o a Hal-WaveDipole

Tt8

1=0=t


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E feld Lines o a Hal-WaveDipole

Tt

4

1= Tt

8

3=


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hort Dipole Antenna

Antena dipole pendek digunakan pada frekuensi

rendah ketika besar. onduktor linear pendeksering disebut dipole pendek.

d

I

/0

-0

aluran #ransmisi rangkaian ekivalen

% 11 % 22 d


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hort Dipole Antenna )samb*


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hort Dipole Antenna )samb*


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!eberapa karakteristik Dipole

Antenna


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Dipole vs. Ideal & Short Dipole2/

Note: For an antenna of length L, that carriers anaxial uniform current

sohmic Ra

LR

2

fRs 2;2

==

Surface resistance

a2

L

frequency


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!iconical Antenna

Antena ini banyakdigunakan untuk antenamobil.

!erdasarkan chelkunoff:

34 "/ e -5k6 r / "- e 5k6 r

r sin r sin

H4 "/76 e

-5k6 r - "-78 e5k6 r

r sin r sin

9c4 +6 ln cot 6


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"ylindrical Antenna

Perbandingan Biconical

Antenna dengan

Cylindrical Antenna:

Mudah difabrikasi

dibandingkan biconical

antenna

!andwidth biconical lebihlebar )wide-angle*


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!ow #ie Antenna

imple antenna to cover the H$ #; "hannels )fre0 ?66 MH@*


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Folded DipoleAntena

Antena ini banyak digunakan sebagai antena #;

Daya pancarnya : r 4


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Folded DipoleAntena (samb

a. #he $olded dipole antenna

b. 3ven 3Bcitation

c. 8dd 3Bcitation


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Antena !onopole ("ro#nded Dipole

Antena monopole merupakan setengah dariantena dipole yang berada di atas permukaan

bumi

!anyak digunakan untuk :

F siaran komersial pada AM-band )=66-+=66 H@*F pelayanan komunikasi land mobile

Antena monopole terdiri dari + antena dipole

yang diletakkan di atas bumi )biasanya dimenara*dengan menggunakan +< pan5ang

gelombang)0uarter wave antenna*.

(esistansi radiasi ideal 4 C,=


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Antena !onopole(samb


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Antena !onopole(samb

A monopole antenna with

four radial >arm ground

screen

'round creen digunakan

untuk menghindari power

loss karena konduktivitas

pentanahan yang buruk


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Antennas above a PerectGrond Plane

I!a"e #heor$ & %onopole In many practical situations, antennas are mounted onground planes

In practice, ground planes are metallic nite size and maynot be planar

useful approximation that allo!s the application of image

theory is to assume that the ground plane is "innite# inextend and perfectly conducting $%&'&()

ntenna

*roundplane

ntenna

*roundplane

Innite ground plane

ntenna

%&'&(


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Antennas above a PerectGrond Plane

I!a"e #heor$ & %onopole

In the upper hemisphere, monopole creates exactly thesame electromagnetic elds as the dipole

Image theory allo!s one tocreate equi+alent no!nproblem

Innite ground plane

monopoleantenna

%&'&( 'qui+alent

Idealmonopole

dipole

dipoleAmonoA

mono DD 2

2

1

44

,,

=

=

= -irecti+ity of a

monopole ist!ice of dipole

22

,, )(40

2

1

h

RR dipolermonor == Length of monopole

dipole


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Antena Loop

Antena %oop ini terdiri dari berbagai konfigurasi

namun karena konstruksi dan kesederhanaan dalam

analisis, loop berbentuk lingkaran paling populer dan

menarik perhatian untuk ditelaah.

Disini diasumsi loop antena

ekivalen dengan dipole pendek

dalam menganalisa daerah 3

dan H -nya.ada antena loop, medan yang

ada 3dan H34 6 dan 3r 4 6

H4 6 dan Hr 4 6


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Antena Loop (samb


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S!all Loop Antennas Small loop

antennas :

It turns out that the radiation elds of small loops

are independent of the shape of the loop anddepend only on the area of the loop

.ector potential :

==C

rrj

rj

rrj

V

rj

dcer

edver

e '4

'4

''

'

IJA

Note : It appears to be easier to construct Afor thesquare loop

%erimeter , uniform time +arying current


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S!all Loop AntennasSare Loop

Small square loop can be thought ofas combination of "/# ideal dipoles&

xI

01

02

0/

03y

z 1R

r

4321 AyAxAyAx

squaresmall +++=A

or

=

=

42

31

42

31

4

4

R

e

R

eIlA

R

e

R

eIlA

RjRj

y

RjRj

x

Far eldapproximation:

for amplitude term:

RRRRR 4321

forphaseterm :

cossin2

cossin2

sinsin2

sinsin2

4

2

3

1

lrR

lrR

lrR

lrR

+=

=

=

+=


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S!all Loop AntennasSare Loop

4hen : [ ]

sinsin)2/(sinsin)2/(

4

ljljrj

x eer

IleA =

)(2

1sin jj ee

j

=5ecall :

Finally :

=

sinsin

2sin

42 l

rIlejA

rj

x

=

cossin

2sin

42

l

r

IlejA

rj

y

cossin2

l

)(2

smallfor


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S!all Loop 's. IdealDipole

x

I y

z

x

mI

y

z

x

Iy

zLoop

area S# #

Ideal magneticdipole along zaxis

Ideal dipolealong z axis

small loop in x6y plane

I"j#Im =-ene

ohm"

R

d$D

%&

r

e#Ij

re#Ij

r

A

o

rj

m

rj

m

2

2

280

7!1or2

3

3

8

"0

sin4

sin4

=

=

=

=

=

=

H

E

ohm#

R

d$D

%&

r

e#Ij

re#Ij

r

A

o

rj

rj

2

280

7!1or2

3

38

"0

sin4

sin4

=

=

=

=

=

=

H

E

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