Engineering, 2010, 2, 85-90
doi:10.4236/eng.2010.22011 Published Online February 2010 (http://www.scirp.org/journal/eng).
Experimental Study of Stacked Rectangular Microstrip
Antenna for Dual-Band
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
A dual-band characteristic of stacked rectangular microstrip antenna is experimentally studied. It is a probe
fed antenna for impedance matching with 50Ω coaxial cable. This antenna works well in the frequency range
(2.86 to 4.63 GHz). It is basically a low cost, light weight medium gain antenna, which is used for mobile
communication. The variations of the length and width (1mm) of the stacked rectangular patch antenna have
been done. And it is found dual resonance with increasing lower resonance frequency and almost constant
upper resonance frequency with increases of the length & width of rectangular microstrip antenna. The input
impedance and VSWR, return loss have been measured with the help of Network analyzer.
Keywords: Microstrip Antenna, Stacked Patch Antenna, Dual-Band Antenna, Network Analyzer, Bandwidth
1. Introduction
The demand for application of microstrip antenna in
various communication systems has been increasing
rapidly due to its lightweight, low cost, small size, ease
of integration with other microwave components [1–4].
Microstrip antenna gained in popularity and become a
major research topic in both theoretically and experi-
mentally. However one of main disadvantages of micro-
strip antenna is their narrow band width. It is well known
that the multilayer structure is useful method to improve
these problems. The researcher have investigated their
basic characteristics and extensive efforts have also been
developed to design of electromagnetically coupled two
layer elliptical microstrip stacked antenna [5], stacked
square patch antenna for Bluetooth application [6] and
analysis of stacked microstrip rectangular microstrip
antenna [7]. Several methods have been presented in the
last years to improve it, s such as: thicker substrate [8]
reactive matching network [9], and stacked patches
[10–12]. Microstrip patch antenna elements with a single
feed are used in many popular for various radar and
communication system such as synthetics aperture radar
(SAR), dual-band, multi-band, mobile communication
system and Global Positing Systems (GPS) [13]. It may
be mentioned that the bandwidth can also be improved
by stacking a parasitic patch on the fed patch [14].
Therefore in this present paper, we observed on an elec-
tromagnetically stacked rectangular microstrip antenna
with number of parasitic elements. By using two stacked
patches with the wall at edges between the two patches,
one can obtained enhance impedance bandwidth. Ex-
perimental work is carried out to study the effect of
stacking on various parameters of antenna.
2. Antenna Design Calculation
The transmission line model is used to design rectangular
microstrip antenna which is stacked one by one. Rectan-
gular microstrip antenna (RMA) is designed by using
following procedures.
2.1. Patch Width and Patch Length
The first to design the patch is choosing a suitable di-
electric substrate of suitable thickness. For rectangular
microstrip antenna, the width W and the length L de-
pends on the resonant frequency
r
f
and the parameters
of the substrate employed [1].
To design the rectangular patch width of the antenna is
given by
2
1
2
1
2













r
r
ε
f
c
W (1)
where C= velocity of light
W = width of the microstrip patch
r

= Dielectric constant of the substrate Length of the
resonant element is given by

86 R. K. VISHWAKARMA ET AL.
lΔ
εf
c
L
effr
2
2


 (2)
where
eff

= Effective dielectric constant of the substrate
l = Line extension
eff

and can be expressed as
l
50
10
1
2
1
2
1.
rr
eff W
h εε
ε







 





 






























 258.0
3.0
813.0
262.0
412.0
eff
eff
h
W
h
W
hl


where, h is the thickness of the substrate.
The driven patches were designed to operate at a reso-
nant frequency of 3.0 GHz, their length and width were
calculated to be L= 23.01mm and width W= 30.01mm
respectively. The remaining five patches were designed
with the differences of 1mm in the length and width with
increasing mode. They are stacked in the manner shown
in (Figure 1).
2.2. Feeding Design
The feeding point was designed for lower patch to match
the (50 Ω) coaxial cable feed and the patch. The feeding
point was fabricated along the length of the patch. The
input conductance of the patch fed on the edge slot will
be twice the conductance of one of the edge slots as
suggested by Harrington and given by [15].








 24
1
2
0
khW
G


(3)
where


120
0
2


k 
0

Wavelength of free
space
So the input impedance of the patch is given by
R1= 1/2G (Ω), where G is radiation conductance.
So the upper patch is parasitic and the lower patch is fed
with a co axial probe at the position (X0, Y0) where X0=
6.40 mm and Y0= 15.725 mm. All the designed patches
have been stacked one over the driven patch.
3. Experimental Measurements
The rectangular microstrip antenna was measured using
network analyzer [Agilent E8363B A.04.06]. For ob-
taining the desired dual-frequency behavior the lower
patch conductor of the coaxial feed is allowed to pass
through a clearance hole in the lower patch and is then
eclectically connected to the upper patch as shown in
(Figure 1). The rectangular microstrip consists of one
driven patch and five parasitic patches designed for 3.0
GHz. The variation of length and width with design fre-
quencies of antennas are shown in the Table 1. The
Upper Patch
W
1
Lower Patch
L
1
h
h
Lower Patch
Upper patch
Ground plane
Coaxial feed
Substrate
Figure 1. The dual-band electromagnetically coupled stack-
ed antenna. (a) Upper patch and Lower patch; (b) Cross
section.
Table 1. variation of length and width with design frequencies of patches.
Patches in mm
Dimension of patch Length and width (mm) Design frequency in GHz
Antenna
(Driven patch) 23.01 x 30.15 3.0
Patch 1 24.01 x 31.15 3.0
Patch 2 25.01 x 32.15 3.0
Patch 3 26.01 x 33.15 3.0
Patch 4 27.01 x 34.15 3.0
Patch 5 28.01 x 35.15 3.0

R. K. VISHWAKARMA ET AL. 87
Table 2. Variation of upper and lower resonance frequencies and their ratio (f2/f1) with return loss in dB.
Patches
in mm
Lower
resonance frequency
f1 (GHz)
Upper
resonance frequency
f2 (GHz)
Ratio of resonance
frequencies
f2 / f1 (GHz)
Return loss(dB)
for f1 (GHz)
Return loss(dB)
for f2 (GHz)
Patch 1 2.868 4.585 2.868 -9.99 -12.24
Patch 2 2.904 4.625 2.904 -11.85 -14.24
Patch 3 2.903 4.593 2.903 -10.89 -12.65
Patch 4 2.917 4.624 2.917 -13.26 -14.46
Patch 5 2.917 4.636 2.917 -13.80 -14.45
variation of upper and lower resonance frequencies and
their ratio (f2/f1) with increasing patch length and width
are shown in the Table 2. In order to study the perform-
ance of the development rectangular microstrip antenna
return loss, resonance frequencies and VSWR were
measured experientially with different number of para-
sitic antenna shown in the Table 2. The broad band width
is achieved about 45% with the stacking of the antenna.
4. Design Parameters
The various design parameters of the antenna are as fol-
lows:
Substrate material used Glass Epoxy
Thickness of the dielectric substrate h = 1.59 mm
(a)
(b)
(c)
(d)
(e)
Figure 2. (a) Variations of input impedance with frequency
for patch dimension 24.01x 31.15; (b) Variations of input
impedance with frequency for patch dimension 25.01x 32.15;
(c) Variations of input impedance with frequency for patch
dimension 26.01x 33.15; (d) Variations of input impedance
with frequency for patch dimension 27.01x 34.15; (e) Varia-
tions of input impedance with frequency for patch dimen-
sion 28.01x 35.15.

88 R. K. VISHWAKARMA ET AL.
(a)
(b)
(c)
(d)
(e)
Figure 3. (a) Variations of VSWR with frequency for patch
dimension 24.01x 31.15; (b) Variations of VSWR with fre-
quency for patch dimension 25.01x 32.15; (c) Variations of
VSWR with frequency for patch dimension 26.01x 33.15; (d)
Variations of VSWR with frequency for patch dimension
27.01x 34.15; (e) Variations of VSWR with frequency for
patch dimension 28.01x 35.15.
Relative permittivity of the substrate 
r = 4.
Design frequency f = 3.0 GHz
Thickness of the patch t = 0.0018cm
And designed values were calculated using the stan-
dard equations, which are given below.
The width of the rectangular patch (Driven Patch) W1 =
30.15 mm.
The length of the rectangular patch (Driven Patch) L1
= 23.01 mm.
The variation of length of the patch (Parasitic Patch) L
= 24.01 mm to 28.01 mm.
The variation of width length of the patch (Parasitic
Patch) W = 31.15 mm to 35.15 mm.
5. Discussion of Results
1) The variation of input impedance with frequency for
rectangular dimensions (Patch 1 to Patch 5) is shown in
Figures 2(a) to 2(e). It is observed that stacked patch an-
tenna shows dual resonance in which lower resonance
frequency increases with increasing patch dimensions
frequencies increase with increasing the patch dimensions.
2) The variation of VSWR with frequency for rectan-
gular dimensions (Patch 1 to Patch 5) is shown in Fig-
ures 3(a) to 3(e) It is observed that the value of VSWR
corresponding to lower resonance frequency is decreases
from 1.96 to 1.54 with increasing patch dimensions
where as at the upper resonance frequency the value of
VSWR is also decrease from 1.66 to 1.47.
3) The variation of resonance frequencies with different
dimensions of the antenna (Patch 1 to Patch 5) are shown
in the Figure 4, It is observed that both resonance fre-
quencies increase with increasing the patch dimensions.
4) The variation of resonance frequency ratio f2/f1 with
dimensions of the antenna (Patch 1 to Patch 5) is shown

R. K. VISHWAKARMA ET AL. 89
in the Figure 5. It is observed that both ratios of reso-
nance frequencies are all most constant with increasing
the patch dimensions.
5) The variation of different dimensions of the antenna
(Patch 1 to Patch 5) with real part of input impedance is
shown in Figure 6. It is observed that the real part of in-
put impedance is decrease from 91.27 to 71.20 at lower
resonance frequency and increases as 31.87 to 34.78 with
increasing the patch dimensions.
6. Conclusions
This paper has investigated the effect of introducing di-
mensions variation of parasitic patches on the perform-
ance of an electromagnetically coupled stacked rectangu-
lar microstrip antenna. The dual-band operation is achi-
eved. It is observed from the experimental result that the
resonance frequencies ratio all most constant (2.86 to 2.91
GHz) with increasing the patch dimensions. The broad
band width is also achieved 45% of the rectangular mi-
crostrip antenna by stacking the patches. Therefore the
proposed antenna can be used for mobile communication.
where as upper resonance frequency is almost constant
with increasing the patch dimensions.
2.5
3
3.5
4
4.5
23 45
Dimension of patches (mm
)
6
f
1
f
2
Resonance frequencies (GH
z
)
Figure 4. Variation of resonance frequencies with different patch dimensions.
1.5
1.6
1.7
1.8
1.9
2
22.5 33.5 44.5 55.5
6
Dimension of patches (mm)
Ratio of resonance frequencies (GHz)
f
2
/f
1
Figure 5. Variation of ratio resonance frequencies with different patch dimensions.

90 R. K. VISHWAKARMA ET AL.
30
40
50
60
70
80
90
2345
Dimension of patches (mm)
Real part of input impedance (ohm
)
6
R_part (f
1
)
R_part (f
2
)
Figure 6. Variations of patch dimensions with real part of input impedance.
7. Acknowledgments
The authors would like to thank Professors Arun Kumar
and Shri R. K. Malaviya of the Space Application Centre,
Indian Space Research Organization Ahmedabad, for
providing the measurement facilities.
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