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1. D. Ujwala et al Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 3( Version 1), March 2014, pp.102-105
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Wideband Coaxial Fed Rotated Stacked Patch Antenna for
Wireless Applications
D. Ujwala1
, A. Gnandeep Reddy2
, J. Kowsik Sasthre2
, K. Gopivasanth Kumar2
,
K. Sai Chandra2
1
Assistant Professor, Department of ECE, K L University, Guntur Dt., A.P, India
2
Students, B. Tech, Department of ECE, K L University, Guntur Dt., A.P, India
Abstract
A novel circularly polarized coaxial fed rotated stacked patch antenna is proposed and its performance
characteristics are presented in the current work. The antenna consisting of four parasitic patch, each one being
rotated by 300
relative to its adjacent patches. The proposed antenna is giving return loss less than -10 dB with
VSWR<2 and bandwidth 700 MHz (5.8 to 6.5 GHz) with axial ratio less than 3dB. The analysis of the antenna
is explained through parametric study and HFSS simulation results are presented in the current work.
Keywords: Coaxial Feeding Rotated Stacked Patch, Performance Characteristics.
I. Introduction
Miniaturization of microstrip patch antennas
(MPAS) is a very challenging field to investigate due
to the increasing interest in integrating such antennas
in MMIC circuits. The conventional dimensions of
MPAS are around a half waveguide wavelength.
Several miniaturization techniques are appearing to
reduce such dimensions. These techniques can be
classified in: 1) Use of high permittivity substrates;
2) Use of magnetic substrates; 3) Increase electrical
length; 4) Short-circuits; 5) Superstrates and 6)
Combinations of them [1]. Using high permittivity
substrates, the antenna size can be considerably
reduced. One of the main problems is the surface-
wave mode excitation causing a reduction of surface-
wave radiation efficiency. Moreover, as the substrate
has finite dimensions, the diffracted field due to the
surface-wave mode, degrades the radiation pattern
increasing the side-lobe level and increasing also the
cross polar field. In arrays, the mutual coupling
caused by surface wave modes limits beam-steering
[2].
One of the methods of generating circular
polarization with broad AR bandwidths is the
application of stacked multilayered patch structures.
In [3]–[5], various configurations of stacked patch
antenna structures have achieved dB relative
bandwidths of 13.5%, 9.6%, and 13.5%, respectively.
In [6], a microstrip antenna composed of an L-shaped
feed network, a wide slot, and a parasitic patch has
obtained a bandwidth of 45% with a gain of 4 dBic.
However, the antenna radiates in a bidirectional
radiation pattern. Among microstrip antennas,
aperture stacked patch (ASP) antennas [7]–[10] are
appealing due to their wide-VSWR bandwidth. In
this paper, a novel method is presented for the
generation of circular polarization by a modification
of an ASP antenna composed of four patches, each
one being oriented at an angle of 30 with respect to
its adjacent lower and upper patches. The advantages
of the proposed antenna are its high gain, wide CP
bandwidth, simple design, ease of fabrication, and
appropriate geometry to be used in an array
configuration.
Fig 1 Coaxial Fed Rotated Stacked Patch Antenna
RESEARCH ARTICLE OPEN ACCESS

2. D. Ujwala et al Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 3( Version 1), March 2014, pp.102-105
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Fig 2 Side View of the Model
II. Antenna Specifications
Fig 1 and 2 shows the proposed antenna model with
rotated stacked patches and side view of the antenna.
The stacked patches are taken on FR4 substrate
materials with separation of 1.6 mm thickness of each
substrate. Table 1 shows the antenna specifications.
S. No Specification
1 4-Layers
2 All are FR-4 Substrates
3 3 air gaps
4 Patches are rotated 30 degrees consecutively
5 Feed location: (-5mm, 4mm)
6 Dimensions: 35mm x 35mm x 1.6mm
7 Patch dimensions: 22mm x11mm
III. Results and Discussion
5.00 6.00 7.00 8.00
Freq [GHz]
-40.00
-30.00
-20.00
-10.00
0.00
dB(St(1,1))
stacked patch antennaReturn Loss ANSOFT
m1 m2
m3
m4
Curve Info
dB(St(1,1))
Setup1 : Sw eep1
feedX='-5mm' feedY='4mm'
Name X Y
m1 5.8859 -10.3111
m2 7.5772 -10.1583
m3 6.1879 -35.0783
m4 7.2550 -17.5821
Fig 3 Return loss Vs Frequency and Smith Chart
5.00 5.50 6.00 6.50 7.00 7.50 8.00
Freq [GHz]
0.00
1.00
2.00
3.00
4.00
5.00
VSWRt(coax_pin_T1)
stacked patch antennaVSWR ANSOFT
m1
m2
Curve Info
VSWRt(coax_pin_T1)
Setup1 : Sw eep1Name X Y
m1 6.1879 1.0359
m2 7.2550 1.3044
Fig 4 VSWR and 3D gain of the Antenna
The input impedance smith chart for the
proposed antenna and return loss simulated at
selected frequencies is shown in the figure (2). The
return loss curve shows the amount of energy that is
lost at the resonating frequencies when load is
connected. The frequency responses of the reference

3. D. Ujwala et al Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 3( Version 1), March 2014, pp.102-105
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antenna-namely gain, VSWR and AR—versus
frequency are shown in Fig 5 and 7. Circular
polarization is achieved if two perpendicular
components are simultaneously excited with equal
amplitude and ± 900
out of phase. By rotating each
patch, both components of a linear polarization, i.e.,
aɑx and ɑy, are excited and the distances between
patches lead to a phase difference between adjacent
patches.
-200.00 -150.00 -100.00 -50.00 0.00 50.00 100.00 150.00 200.00
Theta [deg]
-15.00
-12.50
-10.00
-7.50
-5.00
-2.50
0.00
2.50
5.00
7.50
dB(GainTotal)
stacked patch antenna2D Gain ANSOFT
m1 Curve Info
dB(GainTotal)
Setup1 : Sweep1
Freq='5GHz' Phi='0deg'
Name X Y
m1 10.0000 5.8866
5.00 5.25 5.50 5.75 6.00 6.25 6.50 6.75 7.00
Freq [GHz]
-3.00
-2.00
-1.00
0.00
1.00
2.00
3.00
4.00
5.00
6.00
dB(GainTotal)
stacked patch antennaGAIN ANSOFT
m1 m2
m3
m4
m5
m6
m7
Curve Info
dB(GainTotal)
Setup1 : Sweep1
Phi='180deg' Theta='0deg'
Name X Y
m1 5.0201 5.6803
m2 5.1812 5.5508
m3 5.6040 5.2205
m4 6.0671 4.5873
m5 6.4698 3.6924
m6 6.7315 2.9858
m7 6.9128 3.1561
Fig 5 2D gain curve and Frequency Vs Gain Curve
Antenna radiation pattern is the display of
the radiation properties of the antenna as a function
of spherical coordinates (, ɑ). In most cases the
radiation pattern is determined in the far field region
for constant radial distance and frequency. For a
linearly polarized antenna, the E and H planes are
defined as the planes containing the direction of
maximum radiation and the electric and magnetic
field vectors respectively. Figure 6 shows the
radiation pattern of the antenna in E and H plane.
Fig 6 Radiation Pattern in E and H Fields
Observe that the antenna with a single patch
can also generate a circularly polarized radiation
pattern. In this case, the patch should be oriented at
the angle of 45 relative to the feed slot.
-200.00 -150.00 -100.00 -50.00 0.00 50.00 100.00 150.00 200.00
Theta [deg]
0.00
10.00
20.00
30.00
40.00
50.00
60.00
dB(AxialRatioValue)
stacked patch antennaAxial Ratio ANSOFT
Curve Info
dB(AxialRatioValue)
Setup2 : LastAdaptive
Freq='6.1879GHz' Phi='0deg'
dB(AxialRatioValue)
Setup2 : LastAdaptive
Freq='6.1879GHz' Phi='90deg'
Fig 7 Axial ratio frequency Curve

4. D. Ujwala et al Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 3( Version 1), March 2014, pp.102-105
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Fig 8 Current Distribution of antenna at 6.1 GHz
IV. Conclusion
Circularly polarised microstrip stacked patch
antenna with rotated patches is presented in this
work. The current design is operating with good
performance characteristics and stable gain
throughout the desired frequency band. All the
antenna parameters are simulated using HFSS and
their analytical presentation is given in this paper.
Axial ratio less than 3dB and VSWR less than 2 are
the reasonable things for applicability of this antenna
in the real time environment.
V. Acknowledgments
References
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