Engineering, 2010, 2, 91-96
doi:10.4236/eng.2010.22012 Published Online February 2010 (http://www.scirp.org/journal/eng).
Analysis of Rectangular Notch Antenna for Dual-Band
Operation
Rajesh Kumar Vishwakarma1, Sanjay Tiwari2
School of Studies in Electronics, Pt. Ravishankar Shukla University, Raipur, Chhattisgarh (C.G)
Received August 27, 2009; revised September 14, 2009; accepted September 20, 2009
Abstract
In this paper a design of single layer rectangular notch microstrip antenna for dual-band is proposed and ex-
perimentally investigated. This antenna is excited by microstrip line. Direct microstrip coupling with proper
matching transformer has been used. Design is made for optimized notch dimension for two resonant fre-
quencies. These resonance frequencies change with the variation in length and width of the notch. The input
impedance and VSWR have been measured with the help of Network analyzer. It is found that the input im-
pedance and VSWR depends variation in length and width of the notch microstrip antenna.
Keywords: Microstrip Antenna, Notch Antenna, Dual-Band Antenna, Matching Transformer
1. Introduction
Microstrip antennas are receiving much attention at pre-
sent because they offer many practical advantages such
as small size, lightweight, low cost and a low profile ease
of fabrication and integration with RF devices [1]. In the
recent years, radar, satellite communication wireless net-
works such as global positioning system (GPS), synthetic
aperture radar (SAR), often require dual frequency patch
antenna to avoid the use of two different antennas. An
ideal dual-frequency antenna should have similar per-
formance in both operating modes. One of the principal
disadvantages of such antenna is narrow bandwidth. Re-
cently several papers [2–4] have been published treating
notch microstrip antenna to achieve dual band character-
istics. The major limitation of microstrip antenna lies in
its limited bandwidth. Several methods have been re-
ported in the literature [5–7] to improve the bandwidth of
the microstrip antenna such as thicker substrate use of
parasitic elements, proximity coupling of the feed line,
and stacked microstrip antennas. Recently Palit [8] et al
has reported a microstrip antenna by properly cutting a
notch inside the radiating element. This properly fields
enough BW for dual band frequency and broadband op-
eration. In this case dual resonance is obtained by a dipole
loaded notch antenna [9], notch loaded patch antenna [10],
and notch triangular microstrip antenna [11] at the radiat-
ing edge of patch. The idea is extended by designing
variation of length and width of the notch antenna. In the
present work, and the effect of notch length and width on
the resonance frequencies have been carried out.
2. Feeding Network
The microstrip line method is easy to fabricate simple to
model and match by controlling the inset cut position in
the patch in the (Figure 1). Matching transformers trans-
form the input resistance of patch to 50 ohm coaxial ca-
ble. The ratio W/h of the microstrip line used for feeding
network can patch to found as to follows. The effective
dielectric constant change with the ratio of strip width W
to thickness h as [12]
0.5
w
h10
1
2
1
r
ε
2
1
r
ε
eff
ε

























 (1)
when then define
effo εZZ  (2)
where Z is the strip impedance. The formula for Z0 = for
W/h 1can be given as





 4h
w
w
8H
60InZ0for 1
h
W (3)
6
0
W
h
1
W
h
0.442.42
h
W
120π
Z






for 1
W
h (4)
We can find the impedance when W/h is known but most
design problem required the otherwise i.e. give Z

R. K. VISHWAKARMA ET AL. 92
L
W
N
otch
Feed Point
L
1
W
1
4/
g

Figure 1. The notch rectangular microstrip antenna.
fin W/h, So Equations (1) and (3) or (4) in an interactive
process are used to find W/h when W/h =1, We first find
Z0 of W/h =1 and then eff

and impedance are calculated
as.

















2
1
r
ε
2
1
r
ε
eff
ε 1
h
W (5)
effo ZZ
 
and
)1(
effo ZZ
  (6)
where





 16.126
0h
W
Z
If Z0 is greater than Z0 (1) then W/h using is less or
equal 1
Case 1 When 1
h
W then






















 





8
60
Z
exp
60
Z
exp2
h
W2
00 (7)
starting with


1
eff

we solve for
h
Wusing this
value. We find 





h
W
eff

from equation. Then it is sub-
stituted back in 13 to find a new value of
h
W
Case 2 when 1
h
W we use Newton’s method of the
finding function zero to form an integration equation.
Let X= 





h
W





































 




44.0
1
1644.0
1201
142.21
5
2
0
6
2
X
X
ZX
XX
X
h
W
new

(8)
using the new h
Wwe find h W
eff
 and a new value of
. A good starting value for the iteration is found from
0
Z
198
120
0
 Zh
W (9)
Iteration method has been done from Equations 1 to 9
and converges in a few cycles.
3. Measurement Techniques
The network analyzer is used to perform the measure-
ment. Glass epoxy substrate with thickness of h=1.59
mm and approximate dielectric constant 5.4

r

was
used. Several patches were fabricated with the variation
of notch length and width. The variation of lower and
upper resonance frequencies with notch length and width
are shown in the Figures 6(a) and 6(b). The variation of
upper and lower resonance frequencies ratio (f2/f1) with
notch length and width are shown in the Figures 7(a) and
7(b). The resulting data are shown in Tables 1 to 2.
4. Design Procedure and Design Parameters
The actual dimension of the antenna designed is magni-
fied two times in order to achieve the desired accuracy in
the final design. The antenna shape of enlarged dimen-
sion is taken times in rubylith film. This enlarge shape is
photo reduced using a high precision camera to produce
a high-resolution negative, which is later used for ex-
posing the photo resist. The laminate is cleaned to insure
proper adhesion of the photo resist and necessary resolu-
tion in the photo development process. The photo resist
is now applied to both sides of the laminate using a
laminator. After wards, the laminate is allowed to stand
to normalize to room temperature prior to exposure and
development. The photographic negative is now held in a
very close contact with the cover sheet of the applied
Table 1. Variation of resonance frequencies with notch
length for a given width =10mm.
Length
(mm)
Frequency
(f1) GHz
Frequency
(f2) GHz
Frequencies
ratio
(f2/f1) GHz
2 2.998 4.525 1.527
3 2.993 4.606 1.613
4 3.01 4.523 1.513
5 3.01 4.619 1.609
Table 2. Variation of resonance frequencies with notch
width for a given length =2mm.
Width
(mm)
Frequency
(f1) GHz
Frequency
(f2) GHz
Frequencies
ratio
(f2/f1) GHz
6 2.955 4.497 1.542
7 2.930 4.522 1.592
8 2.953 4.534 1.581
9 2.962 4.535 1.572

R. K. VISHWAKARMA ET AL.93
photo resist, to assure the fine line resolution required
with exposure to proper wave length light, polymeriza-
tion of the exposed photo resist occurred, making it in-
soluble in developer solution. The backside of the an-
tenna is completely exposed without a mask, since the
copper foil is retained to act as a ground plane. The pro-
tective cover sheet of the photo resist is removed and the
antenna is now developed in developer, which remove
the soluble photo resist material.
Then the antenna is etched. Visual inspection is used
to assure proper etching. Then excess photo resist is re-
moved using a stripping solution. For stack antenna, the
passive antenna are made with single side PCB same as
done for active antenna.
The various design parameters of the antenna are as
follows:
Substrate material used Glass Epoxy
Thickness of the dielectric substrate h = 1.59 mm
Relative permittivity of the substrate 
r = 4.5
Design frequency f = 3.0 GHz
Thickness of the patch t = 0.0018cm and designed val-
ues were calculated using the standard equations, which are
The width of the rectangular patch W = 30.15 mm
The length of the rectangular patch L = 23.04 mm
The length of the notch L1=1.0 mm to 5 mm at fixed
width = 10mm
The width of the notch W1= 6 mm to 10 mm at fix-
edlength = 2 mm
5. Discussion of Results
1) The variation of input impedance with frequency for
different notch length for a given width is shown in Fig-
ures 2(a) to 2(d). It is observed that notch microstrip an-
tenna shows dual resonance in which lower and upper
resonance frequencies increases with increasing notch
length from 2mm to 5mm.
2) The variation of input impedance with frequency
for different notch width for a given length is shown in
Figures 3(a) to 3(d). It is observed that notch microstrip
(a)
(b)
(c)
(d)
Figure 2. (a) Variations of input impedance with frequency
for notch length=2mm at width =10mm; (b) Variations of
input impedance with frequency for notch length=3mm at
width =10mm; (c) Variations of input impedance with fre-
quency for notch length = 4mm at width =10mm; (d) Varia-
tions of input impedance with frequency for notch
length=5mm at width =10mm.

R. K. VISHWAKARMA ET AL. 94
antenna shows dual resonance in which lower resonance
frequency increases with increasing notch width from
6mm to 9mm,where as upper resonance is all most con-
stant with varying notch width.
(a)
(b)
(c)
(d)
Figure 3. (a) Variations of input impedance with frequency
for notch width = 6mm at length =2mm; (b) Variations of
input impedance with frequency for notch width = 7mm at
length =2mm; (c) Variations of input impedance with fre-
quency for notch width = 8mm at length =2mm; (d) Varia-
tions of input impedance with frequency for notch width =
9mm at length =2mm.
3) The variation of VSWR with frequency for differ-
ent notch length for a given width are shown in Figures
4(a) to 4(d) It is observed that the value of VSWR cor-
responding to lower resonance frequency is decreased
from 1.27 to 1.11 with increasing notch length where as
(a)
(b)
Figure 4. (a) Variations of VSWR with frequency for notch
length = 2 mm and 3 mm notch at width =10 mm; (b)
Variations of VSWR with frequency for notch length = 4
mm and 5 mm at notch width =10 mm.

R. K. VISHWAKARMA ET AL.95
corresponding to the upper resonance frequency the
value of VSWR is increased from 1.10 to 1.69.
4) The variation of VSWR with frequency for differ-
ent notch width for given length are shown in Figures 5(a)
to 5(d). It is observed that the value of VSWR corre-
sponding to lower resonance frequency is decreased from
1.12 to 1.08.
5) The variation of resonance frequencies with notch
dimensions is shown in the Figures 6(a) to 6(b). It is ob-
served that both resonance frequencies are increased with
notch dimensions.
6) The variation of resonance frequency ratio f2/f1 with
notch dimensions is shown in the Figures 7(a) to 7(b). It
is observed that both resonance frequencies are increases
with notch dimensions.
(a)
(b)
Figure 5. (a) Variations of VSWR with frequency for notch
width = 6 mm and 7 mm at notch length =2 mm; (b) Varia-
tions of VSWR with frequency for notch width = 8 mm and
9 mm at notch length =2 mm.
2.9
3.1
3.3
3.5
3.7
3.9
4.1
4.3
4.5
4.7
234 5
N
otch Length (mm)
f
1
f
2
Frequencies (GHz)
(a)
2.9
3.1
3.3
3.5
3.7
3.9
4.1
4.3
4.5
4.7
6789
f
1
f
2
N
otch widths (mm)
Frequencies (GHz)
(b)
Figure 6. (a) Variations of resonance frequencies with notch
lengths for a given width; (b) Variations of resonance fre-
quencies with notch width for a given length.
1
1.5
2
2.5
3
234 5
N
otch lengths (mm)
f
2
/f
1
Frequency (f
2
/f
1
) (GHz)
(a)
1
1.5
2
2.5
3
6
7 8 9
N
otch widths (mm)
f
2
/f
1
F
requency (f
2
/f
1
) (GHz)
(b)
Figure 7. (a) Variation of frequency ratios (f2/f1) with notch
length for a given width; (b) Variation of frequency ratios
(f2/f1) with notch width for a given length.
6. Acknowledgment
The authors would like to thank Professor Arun Kumar
and Shri R. K. Malaviya of the Space Application Centre,
Indian Space Research Organization Ahmedabad, for

R. K. VISHWAKARMA ET AL. 96
providing the measurement facilities.
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