TELKOM
NIKA Indonesia
n
Journal of
Electrical En
gineering
Vol. 14, No. 2, May 2015, pp. 323 ~ 32
8
DOI: 10.115
9
1
/telkomni
ka.
v
14i2.747
9
323
Re
cei
v
ed Fe
brua
ry 8, 201
8; Revi
se
d Ap
ril 13, 201
5; Acce
pted April 29, 2015
U-slot Circular Patch Antenna for WLAN Application
Arsh
ad Wah
a
b*, Jiadong
Xu
North
w
e
s
tern
Pol
y
t
e
ch
nic Un
iversit
y
, 7
1
0
1
2
9
, Shaan
xi, Xia
n
, Chin
a
*Corres
p
o
ndi
n
g
author, e-ma
i
l
: arshad
w
a
h
a
b
90@
gmai
l.com
A
b
st
r
a
ct
A dual-fre
que
n
cy microstri
p
patch ante
n
n
a
s
has bee
n pr
esente
d
an
d used for 80
2.11W
LA
N
app
licati
ons.
T
he ante
nnas
h
ad bee
n desi
g
ned,
s
i
mul
a
te
d
an
d p
a
ra
metrically st
udi
ed
in
CST
Microw
a
v
e
studio. By intro
duci
ng u-s
l
ot, dua
l-ba
nd o
per
ation w
i
th
its o
perati
ng
mo
de
cent
ere
d
at frequ
ency 2.4G
H
z
,
3.65GH
z
a
n
d
5.2GH
z
h
ad b
een
obt
ain
ed. T
he
g
a
in
a
nd directivity ha
d bee
n
i
m
p
r
o
v
ed b
y
ad
ju
sti
n
g the
parameters of
the antennas.
The gain of the pro
posed designs was 6.019dB
i, 4.04dBi and
6.22dBi and
directivity w
a
s 6.02dBi, 4.0
5
d
Bi
an
d 6.22
d
B
i at resona
nt frequenc
ie
s
2.4GH
z
, 3.6G
H
z
a
nd 5.2G
H
z
respectiv
e
ly. T
he p
a
tch ante
nnas
had
bee
n prop
ose
d
to
be use
d
in
portab
l
e d
e
vic
e
s that req
u
ir
e
mi
niat
uri
z
e
d
c
o
nstituent p
a
rts.
.
Ke
y
w
ords
: du
al ba
nd, W
L
AN
, circular patch,
antenn
a
Copy
right
©
2015 In
stitu
t
e o
f
Ad
van
ced
En
g
i
n
eerin
g and
Scien
ce. All
rig
h
t
s reser
ve
d
.
1. Introduc
tion
Multiband a
n
t
enna a
r
e wi
dely use
d
in
wirele
ss co
mmuni
cation
system
s like mobile
phon
e, laptop
etc. The si
ze of these de
vices i
s
be
co
ming sm
aller
rapidly du
e to the con
c
ept
of
miniaturi
z
atio
n. Con
s
eq
ue
ntly t
he size
of the anten
na should
be
small to fit insid
e
them.
By
introdu
cin
g
sl
ots in
circula
r
patch
anten
na havin
g si
n
g
le freq
uen
cy
band
ca
n b
e
modified i
n
to
multiband
an
tenna. Th
e si
ze a
nd p
o
siti
on of sl
ot
are impo
rtant i
n
determinin
g
the resona
nce
freque
ncy. T
he
sha
p
e
s
of
the
slots like C, E, F,
H,
L, V, U etc
are
bein
g
u
s
ed for the
de
sire
perfo
rman
ce.
More tha
n
o
ne
slot of
different
shape
s
is u
s
e
d
fo
r dif
f
erent m
u
ltiba
nd a
ppli
c
atio
ns.
The u
-
slot
wa
s u
s
e
d
in
whi
c
h th
e a
n
ten
na p
e
rfo
r
med
wid
eban
d b
e
havior
and
lin
early p
o
lari
ze
d
[1], but they h
a
ve the disa
d
v
antage
s of lar
ge
size and
compli
cation
s in fabri
c
atio
n.
Re
cently ma
ny desi
gn of
dual b
and
pa
tc
h ante
nna
have be
en a
nalyze
d
. For
example
the anten
na i
n
[2] having
rectan
gula
r
p
a
tch a
nd
stra
ight stri
ps
wit
h
differe
nt si
ze. The a
n
ten
na
pre
s
ente
d
in
[3], a microwave su
bst
r
at
e wa
s
used
having b
r
o
a
d
band
characteristic,
but t
he
dimen
s
ion
of
the
gro
und
(120
mm
×
1
00mm)
wa
s l
a
rge
for mo
b
ile devi
c
e
s
. In [4] the
hig
h
freque
ncy p
e
r
forma
n
ces
h
a
ve bee
n im
proved
by m
odified g
r
ou
n
d
plan
e on t
he bottom la
yer
.
CPW fe
d mo
nopol
e ante
n
nas
have b
e
e
n
pre
s
e
n
ted i
n
ord
e
r to
me
et the dual
ba
nd re
qui
reme
nts
like G
-
sha
p
e
d
[4]. The third ban
d
cente
r
ed
at 3.
4 G
H
z u
s
eful fo
r
WiMAX ha
s
been
achieve
d
by
triangul
ar ant
enna having cro
s
s sha
pe
i
n
sid
e
it
[5
]. Many re
se
arche
s
sho
w
th
at the wi
de b
and
cha
r
a
c
teri
stic of the anten
na can b
e
m
ade a
s
multi
band
by ch
a
nging th
e flo
w
of the
surf
ace
curre
n
t in the patch [6
-8]
.
The pin dio
des h
a
ve be
en used in a
n
tenna fo
r switchi
ng bet
wee
n
linear a
nd circula
r
pola
r
iza
t
ion with cha
nging t
he si
ze of the slot
[9].Slots and notch
es loa
d
ed
microstri
p
pat
ch anten
na
fo
r
d
ual ban
d
o
peratio
n
[10],
and
a
finge
r
sha
ped
ante
n
na fo
r
wirel
e
ss
c
o
mmunic
a
tion GSM/
DCS
/IMT [11]. It is
the
fa
ct that
multiban
d
ch
ara
c
teri
stics
can
be
a
c
hie
v
ed
by intelligent placement of
slot in the pat
ch ant
e
nna.
The pa
per i
s
comp
osed of
dual ba
nd u
-
slot
circula
r
path
antenn
as. Th
e resona
nce freque
nci
e
s h
a
ve been shi
fted by chan
ging the si
ze
of
slot. Th
e di
mensi
o
n
s
a
n
d
pe
rforman
c
e
of
the an
tenna have been
carefull
y
analyzed. The
prop
osed a
n
tenna
s h
a
ve the adva
n
tag
e
s of
small
size, light
wei
ght and
ea
se of fabri
c
ati
on,
whi
c
h ma
ke
the desi
g
n
s
suitabl
e for portabl
e devi
c
e
s
like mo
b
ile hand
set, laptop, gami
ng
con
s
ol
e et
c.
The
ban
dwidt
h
of th
e o
perating
b
and
s
h
a
s
suffici
ent t
o
cover the I
EEE802.11a/
b/y
stand
ard
s
of wide lo
cal a
r
e
a
netwo
rks a
pplication
s
.
Evaluation Warning : The document was created with Spire.PDF for Python.
ISSN: 23
02-4
046
TELKOM
NI
KA
Vol. 14, No. 2, May 2015 : 323 – 328
324
2. Ante
nna Design
The value of diele
c
tric
con
s
tant (
ԑ
r) of the su
bstrate of the ant
enn
a A is 4.3 and
B is 2.2.
The len
g
th a
nd wi
dth of th
e gro
und
are
same
as th
at of sub
s
trate.
The g
r
ou
nd p
l
ane reflect
s
the
electroma
gne
tic waves.
Th
e full g
r
ou
nd
plane
creat
e
s
dire
ction
a
l
radiatio
n while partial ground
plane p
r
od
uces omni
-di
r
e
c
tional radiati
on pattern
. T
he excitation
of antenna is given thro
u
gh
coaxial fe
ed
line. The
ca
pacita
n
ces
d
ue to u
-
sl
ot
can
c
ell
ed the
indu
ctan
ce
prod
uce by t
he
coaxial p
r
ob
e
.
The cha
r
a
c
teristics imp
e
dan
ce of co
a
x
ial cable 5
0
ohm ha
s ma
tched
with the
input imped
a
n
ce of the pat
ch ante
nna.
Table
1
sho
w
s the
pa
rame
ters
of the
propo
sed
de
sig
n
s. All the
di
mensi
o
n
s
a
r
e
in mm
and diele
c
tri
c
co
nsta
nt
(
ԑ
r
)
is unitless. The cha
r
a
c
te
ristics of
the
patch
a
n
ten
na
h
a
ve
be
e
n
analyzed by
many param
etric a
nd
si
m
u
lation stu
d
ie
s mad
e
by many re
sea
r
che
r
s
acro
ss the
worl
d [12-14]
. But no empirical formul
as have
b
e
e
n
repo
rted y
e
t. The desi
gn of microstrip
circula
r
patch
anten
na, the
paramete
r
s su
ch as
diel
e
c
tri
c
con
s
tant
(
ԑ
r
), resona
n
c
e f
r
equ
en
cy
(f
r
),
and h
e
ight
(h
) are con
s
ide
r
for d
e
termi
n
ing the
r
adiu
s
of the
patch. The dim
e
n
s
ion
s
of
circu
l
ar
patch a
n
tenn
a are calculat
ed as;
Figure 1. U-sl
ot Patch Antenna with dim
ensi
on varia
b
l
es
Table 1. Para
meters of the prop
osed ant
enna
s
Designs L
W
a
b
c
ԑ
r
r
h
Antenna
A
53
43 17.2
14.2
2.6
4.3 16
5
Antenna
B
53
43
23.4
16.16
2.38 2.2 14.9
4.3
.
(1)
F
.
√
ε
(2)
Whe
r
e F i
s
fri
nging effe
ct whi
c
h ma
ke
s the patch el
ectri
c
ally larg
er. The effe
ctive radiu
s
of
the
antenn
a is:
1
ln
1.7726
(3)
3. Results a
nd Discu
ssi
on
The sim
u
lati
ons h
a
ve be
en ca
rri
ed o
u
t usi
ng
CS
T Microwave
Studio. The reflectio
n
coeffici
ent S
11
of the ante
nna
s is calcu
l
ated in
dB. At
port 1
wh
ere i
nput to t
he ante
nna
h
a
s
applie
d the
scatterin
g
pa
rameter S
11
gi
ves reflection
coeffici
ent
whi
c
h
sho
u
ld
be le
ss th
a
n
-
10dB.The
return
lo
ss of th
e ante
nna
s is sh
own i
n
the
Figu
re
2. In
all resonan
ce
freq
uen
cie
s
t
h
e
return lo
ss o
f
antenna A
and B are le
ss th
an -10d
B. The impe
dan
ce of the
antenna
s a
r
e
illustrate
d in Figure 4, whi
c
h sho
w
that ant
enna
s ha
ve good imp
edan
ce mat
c
hing. Each
curve
Evaluation Warning : The document was created with Spire.PDF for Python.
TELKOM
NIKA
ISSN:
2302-4
046
U-slot Ci
rcula
r
Patch Anten
na for
WLAN
Applicatio
n (Arsh
ad Waha
b)
325
cro
s
s -1
0dB is rep
r
e
s
e
n
tin
g
freque
ncy
band. The
re
turn loss of the anten
na
A is -15.68
d
B
a
t
resona
nt freq
uen
cy 3.65G
Hz
whi
c
h indi
cate
s goo
d impeda
nce m
a
tchin
g
. In 5.2GHz the ret
u
rn
loss of
anten
na B
crossin
g
-10
d
B, but th
e ba
nd
widt
h i
s
(5.10
-
5.40
)
= 3
00M
Hz,
which
is suffici
ent
to match wit
h
IEEE802.11a stan
dard. By changi
n
g
u-sl
ot bro
a
dne
ss the
se
con
d
re
son
a
n
ce
freque
ncy
5.2
5
GHz
can
be
shifted to
5.7
6
GHz b
and.
I
n
ca
se
of ant
enna B thi
s
v
a
riation
cau
s
es
shifting of re
sonan
ce fre
q
u
ency to 2.45
GHz.
2345
67
-1
6
-1
4
-1
2
-1
0
-8
-6
-4
-2
0
2
|S
11|
,
d
B
Fr
eq
ue
nc
y
,
G
H
z
|S
11
|
of
ant
enna A
|S
11
|
of
ant
enna B
Figure 2. Refl
ection
coeffici
ent vs freque
ncy plot of an
tenna A and
antenn
a B
The Voltage
standi
ng wave ratio ca
n be
calc
ulated by
using the foll
owin
g equati
on.
VS
W
R
|
|
|
|
(4)
S
11
is kno
w
n
as
refle
c
tion
coeffici
ent wh
ich i
s
the
co
mplex num
be
r where the
magnitud
e
is u
s
ed
to d
e
termin
e Volta
ge
standin
g
wave
ra
tio. At 2.4G
Hz
ante
nna A
has th
e VSWR valu
e of
1.16 be
cau
s
e of good i
m
peda
nce m
a
tchin
g
as
compa
r
ed to
antenn
a B.
At the reson
ance
freque
ncy
3.65G
Hz the
a
n
tenna
A ha
s the
VSWR va
lue
of 1.1
3
which d
o
e
s
not
sho
w
m
u
ch
variation.
The gain an
d dire
ctivity of p
r
opo
se
d de
si
gns
a
r
e shown in figure 3. Antenna B ha
s lowe
r
gain and di
re
ctivity as compare to antenna A.T
he
gain
s
of antenna A at resonan
ce fre
q
u
ency
2.45G
Hz
an
d 3.65G
Hz are 6.0
2dBi
and 4.05
d
B
i
respe
c
tively. At reson
ance freq
ue
ncie
s
5.25G
Hz th
e
gain of a
n
te
nna
s B is
6.22dBi. Li
kewi
se the
directi
v
ity of antenna A an
d B
are
6.019dBi an
d
4.046dBi at reso
nan
ce f
r
equ
en
cie
s
2
.
4GHz and 3
.
65GHz re
sp
ectively and
at
resona
nce fre
quen
cie
s
5.2
5
GHz; the di
rectivity of the
antenn
a A is 6.22dBi.
2345
67
-1
0
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
8
9
10
Dir
e
c
t
iv
ity
,
d
B
i
F
r
eq
ue
nc
y
,
G
H
z
D
i
re
c
t
i
v
i
t
y
o
f
a
n
t
enn
a
A
D
i
re
c
t
i
v
i
t
y
o
f
a
n
t
enn
a
B
23
45
67
-1
5
-1
0
-5
0
5
10
15
Ga
i
n
,d
B
F
r
eq
uency
,
G
H
z
G
a
i
n
of
antenna A
G
a
i
n
of
antenna B
Figure 3. Dire
ctivity and Gain of antenna
A and antenn
a B
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ISSN: 23
02-4
046
TELKOM
NI
KA
Vol. 14, No. 2, May 2015 : 323 – 328
326
2345
67
0
20
40
60
80
Impe
da
nc
e
Fr
equenc
y
,
G
H
z
I
m
pedanc
e of
ant
enna
A
I
m
pedanc
e of
ant
enna
B
Figure 4. Impedan
ce of ant
enna A and a
n
tenna B
The
prop
osed
a
n
tenna
s
have
di
re
ctional
ra
diation patte
rns. The
mai
n
lobe
s havi
ng
maximum p
o
w
er radiate
di
rectly a
bove t
he p
a
tch,
sh
o
w
n i
n
ea
ch
pl
ot in the
Figu
re 5
an
d 6.
T
h
e
half power b
e
a
m width in t
he elevation
plan is i
ndi
cat
ed in the plot
s. The h
a
lf po
wer
beam
wi
dth
depe
nd
s o
n
t
he di
re
ctivity whi
c
h i
s
de
creasi
ng
wi
th i
n
crea
sing
di
rectivity of the
anten
na. T
h
e
three
dimen
s
ional
radi
atio
n patterns of
the p
r
op
ose
d
de
sign
s
de
monst
r
ate th
at the maxim
u
m
radiatio
n o
ccurs from th
e
top of the
p
a
tch
su
rface.The maxim
u
m po
wer in t
he mai
n
lob
e
is
dire
cted ab
o
v
e the patch.
The dire
ctivity and gai
n
of the anten
na are also sho
w
n in the
3D
radiatio
n pattern.
(a)
(b)
Figure 5. 3D
Radi
ation pat
terns of
a
n
ten
na A (a) 2.45
GHz (b
) 3.65
GHz
Evaluation Warning : The document was created with Spire.PDF for Python.
TELKOM
NIKA
ISSN:
2302-4
046
U-slot Ci
rcula
r
Patch Anten
na for
WLAN
Applicatio
n (Arsh
ad Waha
b)
327
(a)
(b)
Figure 6. 3D
Radi
ation pat
terns of a
n
ten
na B (a) 3.6
G
Hz
(b) 5.2
G
Hz
4. Conclusio
n
Two d
ual b
and u
-
sl
ot circul
ar
patch
antenn
as
have be
en
desi
gne
d for WLA
N
appli
c
ation. T
he dim
e
n
s
ion
s
of th
ese a
n
tenna
s
are
small
and
ha
ve rem
a
rkabl
e pe
rform
a
n
c
e
cha
r
a
c
teri
stics. Th
e a
n
ten
nas have
go
od
return
lo
ss a
n
d
ra
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m
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f
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d thickne
ss of
the
sub
s
trate. By adjustin
g
the
param
eters of
the antenn
a the gain a
nd d
i
rectivity have improved.
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