TELKOM
NIKA
, Vol.14, No
.1, March 2
0
1
6
, pp. 82~8
5
ISSN: 1693-6
930,
accredited
A
by DIKTI, De
cree No: 58/DIK
T
I/Kep/2013
DOI
:
10.12928/TELKOMNIKA.v14i1.2296
82
Re
cei
v
ed
Jul
y
7, 2015; Re
vised Janu
ary
4, 2016; Accepte
d
Ja
nua
ry 15, 2
016
Design of Compact Microstrip U Shape Bandpass Filter
Using Via Ground Holes
Fajri Dar
w
i
s
*
1
, Arief Budi
Santiko
1
, Novita D
w
i Susanti
1
1
Researc
h
Cen
t
er for Electroni
cs and T
e
leco
mmunicati
on
–
Indon
esi
an Institute of Scienc
es (PPET
-LIPI),
Kampus LIPI, Jl. Sangkur
ia
ng
Buil
din
g
20 4
th
floors, Band
un
g, 4013
5 – Ind
ones
ia,
Phon
e/fax: +
6
2
-
22-2
504
66
1/+
62-2
2
-25
0
4
6
5
9
*Corres
p
o
ndi
n
g
author, em
ail
:
fajri.dar
w
i
s@
li
pi.go.i
d
A
b
st
r
a
ct
T
h
is pa
per pr
e
s
ent the
micr
o
s
trip ba
ndp
ass
filt
er usi
ng tw
o U sh
ape r
e
s
onators w
i
th u
s
ing vi
a
grou
nd
hol
es.
T
he b
and
pass
filter w
a
s esta
blish
e
d
us
i
ng t
w
o U sha
pe r
e
sonators
w
i
th
usin
g vi
a gr
ou
nd
hol
es
a
nd dep
l
o
yed on RT
/du
r
oid 60
10 LM ai
ms
to mi
ni
mi
z
e
t
he
di
me
nsi
on of fi
lter. T
he pro
pos
ed filt
er
w
a
s characteri
z
e
d
us
ing
softw
are simul
a
tio
n
. T
he ch
aract
e
ristic of pr
op
o
s
ed filter
is to
dea
l w
i
th req
u
i
r
ed
specific
ation.
Hardw
a
re r
eal
i
z
a
t
i
on w
a
s
do
ne to v
e
rify
th
e char
acteristic
of prop
ose
d
fi
lter. T
he b
and
pass
filter has the di
me
nsi
on of
4.2
mm x 3.8 mm. T
he filter w
a
s
expec
te
d to ha
ve center frequ
ency of 400 M
h
z
w
i
th mi
ni
mum
3dB
ba
ndw
idth
of 1
5
Mh
z
,
ma
ximu
m i
n
serti
o
n l
o
ss of -
1
.5
d
B
an
d VSW
R
l
e
ss tha
n
2. VS
W
R
and
3dB
b
and
w
i
dth on
rea
l
i
z
ed filt
er h
a
ve
a g
ood
a
g
re
em
en
t wi
th
requ
i
r
ed
spe
c
i
f
i
c
ati
o
n
.
Ho
we
ve
r
the
inserti
on l
o
ss
and c
enter fre
que
ncy w
a
s n
o
t ade
qu
ate. T
he re
ali
z
e
d
filt
er has
inserti
o
n loss
of -2.55
4
dB
w
i
th the center freque
ncy of 4
04.71
1 MH
z
.
Ke
y
w
ords
: filter; U shape re
sonator; dur
oi
d
6010
LM; grou
nd ho
les
Copy
right
©
2016 Un
ive
r
sita
s Ah
mad
Dah
l
an
. All rig
h
t
s r
ese
rved
.
1. Introduc
tion
N
o
w
a
da
ys
, de
ve
lo
p
m
en
t of mic
r
o
s
tr
ip
filte
r
s
in
cludin
g
ban
dpa
ss filter i
s
gro
w
in
g
rapidly.
Bandpa
ss filter i
s
a
comp
onent
whi
c
h
is u
s
e
d
to
p
a
ss d
e
si
red
region
freq
ue
ncy
with
cert
ain
cente
r
freq
ue
ncy. In comm
unication sy
stem, band
pa
ss
filter is u
s
e
d
in tran
smitter an
d re
ceiv
er.
High p
e
rfo
r
m
ance of filters is requi
re
d in
rada
r syste
m
.
In radio f
r
eq
uen
cy, filter is de
sig
ned
usin
g lump
e
d
eleme
n
ts
comp
one
nts
su
ch a
s
capacitor and inductor. T
h
i
s
filter has
been im
plement
ed
in coastal surveill
ance radar
in
PPET-
LIPI [1]. Whe
n
de
signi
ng fi
lter u
s
ing l
u
m
ped el
ement
s, the value
s
o
f
capa
cito
r an
d indu
cto
r
th
at
we can acqui
red
from calculate
the
formula, are difficult to obtai
n
in the ma
rke
t
so that we
use
the value
s
cl
ose
to which
desi
gne
d o
r
use
tunni
n
g
compon
ents. Therefore, we
nee
d
the
m
u
ch
effort to fabricate the filter. Due to the probl
em, ano
thers d
e
si
gn
is req
u
ire
d
to overco
me the
probl
em an
d to redu
ce the
co
st of fabrication
The de
sig
n
filter usi
ng mi
cro
s
tri
p
line i
s
u
s
ed by
many re
sea
r
che
r
s [2
-13].
One of
method i
s
U-sha
pe
re
son
a
t
or or it is
call
ed hai
rpin
re
sonator.
Hai
r
pi
n line i
s
a
co
mpact
structu
r
e.
It is obtaine
d by deflecti
ng line re
so
nator like
a
U letter. The
length of re
son
a
tor is
h
a
lf-
wavele
ngth.
For th
e
radi
o fre
que
ncy,
hai
rpin
line
re
so
nator h
a
s
a l
ong
li
ne. It ma
ke
s the
dimen
s
ion
of
filter be
com
e
quite l
a
rg
e
.
Some tech
nique
s h
a
ve
been
don
e b
y
resea
r
ch
er to
redu
ce th
e dimen
s
ion of
filter [8-13]. In [8], fractal Koch g
e
o
m
etry wa
s a
dded in h
a
irpin
resonato
r
. T
h
is
de
sign
can
be
mini
mized
the
dimen
s
ion
a
pproxim
ately 20% f
r
om
the
conve
n
tional
desi
gn. The
square groove
techniq
ue
wa
s u
s
ed
by [9] to miniaturi
z
e the filter a
nd
sup
p
re
ss the
se
co
nd
harmonic. In
[1
0], an inte
rdi
g
ital hai
rpin
resonato
r
wa
s p
r
e
s
ente
d
. It
repla
c
e
s
the
hairpi
n
re
so
n
a
tor to an int
e
rdigital
ca
pa
citor. Th
e oth
e
r techniq
u
e
s
to minimize t
h
e
dimen
s
ion of
filter are wit
h
usin
g via grou
nd
hol
es. It has bee
n pre
s
ente
d
by [11-13]. This
techni
que
ca
n be red
u
ced
the dimen
s
io
n of filter about 35 -37 % a
s
in [11-1
2
].
In this paper,
we desi
gne
d
the bandpa
ss filter for cen
t
er freque
ncy
of 400 MHz
and the
3dB wo
rki
ng
band
width of
15 MHz u
s
ing
U sh
ape
re
s
onator. It is u
s
ed to p
a
ss this fre
que
ncy
for
clo
ck refe
ren
c
e
in DDS system
on ra
dar.
To re
d
u
c
e the
dime
nsio
n of filter we
use three
techni
que
s.
First, we de
cre
a
se the
numbe
r of
reso
nators. In this d
e
si
g
n
, two U
shape
resonato
r
s are used a
s
in
Figure
1. Se
cond, we u
s
e
via grou
nd h
o
les te
ch
niqu
e. And third,
we
Evaluation Warning : The document was created with Spire.PDF for Python.
TELKOM
NIKA
ISSN:
1693-6
9
30
De
sign of Co
m
pact Micro
s
trip U Shap
e Bandpa
ss F
ilter Using Via
Grou
nd Hole
s (Faj
ri Da
rwi
s
)
83
u
s
e
s
u
b
s
tr
a
t
e th
a
t
h
a
s
h
i
gh
e
r
d
i
e
l
ec
tr
ic
t c
o
ns
ta
n
t. F
o
r
th
e
s
u
bs
tra
t
e
w
e
ch
o
o
s
e
R
T
/d
ur
o
i
d
6
010
LM. This su
bstrate
ha
s typical diele
c
tric con
s
tant
of 10.2. Therefo
r
e, wit
h
com
b
ine t
h
e
techni
que
s, the filter
can
be mo
re
co
mpact. Pri
o
r to band
pa
ss filter fab
r
ication, nume
ri
cal
cha
r
a
c
teri
stic of bandpa
s filter was
cha
r
a
c
te
ri
ze
d
by using software
simu
lation. For the
experim
ent, the ba
ndp
ass filter wa
s re
alize
d
an
d u
s
ed SMA
co
nne
ctor in
b
o
th of input
and
output. Finall
y
, the measurement re
sult
s and its analy
s
is
will be pre
s
ente
d
.
2. Filter Desi
gn and Simulation
The ba
ndpa
ss filter wa
s d
e
sig
ned u
s
in
g U sh
ape
reso
nator.
We
called the
U shap
e
resonato
r
as hairpi
n
re
son
a
tor.
Th
e
re
sonator i
s
ma
d
e
u
s
ing
line
s
t
hat defle
cted
like
U l
e
tter
with
the len
g
th i
s
λ
/2. In thi
s
de
sign, th
e b
a
n
dpa
ss filter
h
a
s th
e
cente
r
freque
ncy
of
400 M
H
z. In t
h
is
freque
ncy, filter acquires q
u
ite a long reso
nator
lin
e. It cause the
dimensi
on o
f
filter becom
es
quite larg
e. So the comp
act filter is nedd
ed.
In orde
r to re
duce the dim
ensi
on of filter, t
he filter only use two U
sha
pe re
so
na
tor that
arrang
ed
se
ri
es
with
coupl
e feed
line.
Beside
s t
hat, the m
odel
with usi
n
g
via
grou
nd
hole
s
is
desi
gne
d in
both of lin
e
resonato
r
. F
u
rthe
rmo
r
e
t
h
e sub
s
trate
whi
c
h ha
s highe
r
di
electric
con
s
tant i
s
u
s
ed.
The
filter d
eploy
s o
n
RT/du
r
oi
d 6
0
1
0
LM
s
u
bs
tra
t
e
w
i
th th
e typ
i
c
a
l va
lu
es as
follows
:
a) Diele
c
tri
c
co
n
s
tant
ε
г
= 10.2
b)
Dissip
ation fa
ctor tan
δ
= 0
.
0023
c)
Thickne
s
s of sub
s
trate
= 1.
27 mm
d)
Cop
per
clad
d
i
ng = 35 µm
The p
r
o
p
o
s
e
d
de
sig
n
of b
andp
ass filter is
depi
cted i
n
Figu
re
1. T
he valu
es
of
para
m
ete
r
in this filter design as follows: L
1
= 4.25
mm; L
2
= 27.45 mm; L
3
= 9 mm; S
1
= 4
.
5 mm; S
2
= 0.3
mm; W
1
= W
2
= 1.6 mm; D (ra
diu
s
) = 0.5
mm.
Figure 1. Structure
of b
and
pass filter
Figure 2. Simulation re
su
lt
of bandp
ass filter
The softwa
r
e
simulatio
n
ADS 201
1.10 i
s
u
s
ed to
ch
ara
c
teri
ze the
desig
n an
d to obtain
the optimum perfo
rman
ce
of the filter such a
s
ce
nt
e
r
f
r
eque
n
cy
,
inse
rt
ion lo
ss,
ret
u
rn lo
ss a
nd
workin
g band
width.
T
he pe
rforma
nce
of
band
pa
ss filter i
s
plotted i
n
Fig
u
re
2.
T
he in
se
rtion
l
o
ss
at cente
r
fre
q
uen
cy of 400
MHz i
s
-0.78
3
dB. While
t
he 3 dB
wo
rki
ng ba
nd
with for this filte
r
is 15
MHz
with ran
ge from 3
92.
3 MHz to 407
.3 MHz. Th
e
return lo
ss at cente
r
freq
ue
ncy is -19.16
0 in
both of port
s
input and o
u
tp
ut. It is same
with the VSWR of 1.25.
From th
e
sim
u
lation
re
sult
s, it can b
e
i
n
ferr
ed th
at the
cha
r
a
c
teri
zation
re
sult
s of the
filter have a good pe
rform
a
nce.
3. Realiza
t
io
n and Cha
r
a
c
teri
zatio
n
The
pro
p
o
s
e
d
de
sig
n
of
b
andp
ass filter wa
s fabri
c
at
ed o
n
RT/du
r
oid 6
0
10
LM
in o
r
de
r
to verify the
cha
r
a
c
teri
zati
on of
simulat
i
on result
s. T
h
e pi
cture of
reali
z
e
d
ba
n
dpa
ss filte
r
i
s
depi
cted in
F
i
gure
3. Fo
r
cha
r
a
c
teri
ze
of band
pa
ss
filter, two SM
A con
n
e
c
tors are
solde
r
ed
in
Evaluation Warning : The document was created with Spire.PDF for Python.
ISSN: 16
93-6
9
30
TELKOM
NIKA
Vol. 14, No. 1, March 2
016 : 82 – 85
84
both of ports i
nput and out
put as sh
own
in Figure 3.
For the groun
d hole, we dri
ll with radiu
s
0.5
mm and then
sold
ere
d
.
From t
he Fi
g
u
re
3, we o
b
tain the
dime
n
s
ion
of b
andp
ass filter
of 4.
2 mm x
3.8 m
m
. VNA
Advantest i
s
use
d
to cha
r
a
c
teri
ze th
e re
alize
d
f
ilter. T
he mea
s
u
r
em
ent re
sult
s of
filter are
sh
o
w
n
in Figure 4 till 6. From the result
s,
it see
m
s the
cente
r
freque
ncy of
reali
z
ed filter
is differe
nt wi
th
the si
mulated
re
sult, 4
00 M
H
z.
Whil
e fo
r
reali
z
ed
filter,
the
cente
r
f
r
eque
ncy
i
s
4.711 MHz hig
h
er
than sim
u
lat
ed one. Thi
s
is pro
bably
evoked
by
diele
c
tric
co
n
s
tant of the sub
s
trate
wh
en
desi
gning.
Figure 4 sho
w
s th
e inserti
on lo
ss
cha
r
a
c
teri
stic
of
re
alize
d
filter. In the ce
nter f
r
equ
en
cy
of realized filter, the inse
rtion loss is wo
rse th
a
n
the simulate
d on
e. This is pro
bably cau
s
e
d
by
inapp
rop
r
iate
ness of
RF cable
s
whi
c
h
i
s
u
s
e
d
in
m
e
asure
m
ent and poo
r sol
dere
d
at gro
und
hole. The
3 d
B
workin
g ba
ndwith
of real
ized filt
er i
s
0
.
957 MHz hi
g
h
er tha
n
the
simulate
d on
e
with ran
ge fro
m
397.302 M
H
z to 41
3.25
9 MHz.
Figure 3. Picture reali
z
ed o
f
bandpa
ss filter
Figure 4. Measu
r
em
ent re
sult of inse
rtion loss
The VSWR i
nput and
out
put are d
epi
cted in Figu
re
5 and 6. In G
eneral, the VSWR in
both of po
rts sho
w
s a
good
perfo
rmance with
the values less than
2. The diffe
ren
c
e
perfo
rman
ce
of VSWR in realized filter
comp
ar
ed to VSWR in si
m
u
lated on
e is
prob
ably ca
u
s
ed
by bad co
nne
ction bet
wee
n
transmissio
n line and
co
nne
ctor.
Figure 5. Measu
r
em
ent re
sult of return loss
input
Figure 6. Measu
r
em
ent re
sult of return loss
output
Evaluation Warning : The document was created with Spire.PDF for Python.
TELKOM
NIKA
ISSN:
1693-6
930
De
sign of Co
m
pact Micro
s
trip U Shap
e Bandpa
ss
Filter Using Via
Grou
nd Hole
s (Faj
ri Da
rwi
s
)
85
The results o
f
realized filte
r
and
simul
a
ted re
sult
s sh
ow n
o
t good
agre
e
me
nt espe
cially
at insertio
n lo
ss. Thi
s
is p
r
obably evo
k
e
d
by in accurate of fabricat
ion pro
c
e
s
s.
Comp
are wit
h
anoth
e
r
de
sign [1
3], this pro
p
o
s
e d
e
sign ha
s a
bet
ter pe
rform
a
n
c
e. Th
e
inse
rtion l
o
ss of the p
r
o
p
o
s
ed
de
sign
is 3.013
dB
b
e
tter than
the
d
e
sig
n
in [1
3]
but still n
eed
to
be improved.
4. Conclusio
n
The b
and
pa
ss filter u
s
ing
two
U
sh
ape
reso
nators
wit
h
u
s
ing
via g
r
ound
hol
e h
a
s
b
een
demon
strated
.
The b
and
p
a
ss filter
ha
s b
een fa
bri
c
ated
on
RT/duroi
d 6
0
1
0
LM
diele
c
t
r
ic
sub
s
trate.
Th
e comp
ari
s
on
between
si
m
u
lated
and
re
alize
d
filter h
a
s
bee
n p
r
e
s
ented. F
r
om
the
cha
r
a
c
teri
zati
on
re
sults, it
has be
en
sh
own
that th
e
filter ha
s
a n
a
rrow ba
nd
wi
th with th
e
3
dB
band
width i
s
about
15.957
MHz a
nd
th
e center fre
q
uen
cy of real
ized
filter 4.7
11 M
H
z hig
h
e
r
than simul
a
te
d one.
Ackn
o
w
l
e
dg
ements
I would like to thank to Re
search Center
for Electron
ics and Tel
e
communi
cation
(PPET-
LIPI) for sup
p
o
rt and
coop
e
r
ation.
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