Design of Dual Frequency Antenna For Global Positioning system

IJSRD - International Journal for Scientific Research & Development| Vol. 1, Issue 2, 2013 | ISSN (online): 2321-0613
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Design of Dual Frequency Antenna for Global Positioning System
Priyank Bhambhani1
1
Electronics & Communication Engineering Department
1
Lok Jagruti Institute of Technology, Gujarat, India.
Abstract—In recent years low profile, light weight antennas
are preferred for the applications which need mobility. In
this research the polygonal-shape Microstrip Single Patch
Antenna has been designed for GPS dual resonant
frequencies (GPS L1 1.575 GHz & L5 1.176 GHz band).
Simulated results for main parameters such as return loss,
bandwidth, radiation patterns and gains are also discussed
herein. The Designing, Simulation & Optimization of this
antenna is done in ADS Software. Result of the simulation
shows at 1.575 GHz and 1.176 GHz, the antenna has return
loss at -20.862 dB and -14.162 dB respectively. .
I. INTRODUCTION
A microstrip patch antenna consists of a dielectric substrate,
with a ground plane on the other side. Due to its advantages
such as low weight , low profile planar configuration, low
fabrication costs and capability to integrate with microwave
integrated circuits technology, the microstrip patch antenna
is very well suited for applications such as wireless
communications system, GPS, cellular phones, pagers, radar
systems, and satellite communications systems[1]. The
development of small-integrated antennas plays a significant
role in the progress of the rapidly expanding military and
commercial communications applications. The technology
to support these applications has been made possible by
recent advances in high-density RF and microwave circuit
packaging. As system requirements for faster data
transmission in lighter compact designs drive the technology
area, higher frequency design solutions with large density
layouts require integration of microwave devices, circuitry,
and radiating elements that offer light weight, small size,
and optimum performance. Over the past two decades,
microstrip patch antenna has received considerable attention
for use in personal communication systems applications due
to its compactness among other advantages. Intensive
research has been carried out to develop new techniques to
overcome the microstrip patch antennas drawbacks, the
most restrictive being narrow band. The bandwidth
enhancement and its return loss improvement without
increasing antenna size and production process is important
to apply this antenna to the modern mobile communication
systems and need to be carried out. Many applications in
communications and radars require circular or dual linear
polarization, and the flexibility afforded by microstrip
antenna technology has led to a wide variety of designs and
techniques to fill this need. In recent years, the demand for
compact mobile telephone handsets has grown. Handsets
with size of a pocket have begun appearing in the market
and, as the demand for increased electronic mobility grows,
the need for small handsets will most likely increase. A
small antenna size is required as one of the important factors
in portable mobile communication systems. The Microstrip
Patch Antennas (MPA) is widely being used because of its
low volume and thin profile characteristics in applications
like Global positioning System (GPS) technology, which
has been widely used as a navigation system to determine
the locations, mapping, tracking devices and surveying. In
terms of public used, GPS receiver requires compact,
lightweight, low power, low cost high reliability and with
mobility capability. The size of MPA is basically
determined by its resonance length and width. The reduction
of the patch size can be achieved by using patch substrate
material with very high permittivity and small substrate
height [2]. But, in this case, the low radiation efficiency will
reduce the antenna gain.
In this study, a novel polygonal-shape patch
antenna optimized for simplicity in design and feeding is
proposed. It has characteristic which will meet GPS system
application. Parameters of the antenna such as return loss,
impedance bandwidth, radiation patterns and gains are
discussed in this paper. This paper shows extensive benefits
of 3D view of radiation pattern facility provided by the ADS
software. Furthermore, in order to satisfy the demanded
precision and reliability, a high performance GPS antenna
must be capable to operate at the two GPS frequencies (L1:
1.575 GHz, L5: 1.176 GHz).This demand has prompted
increased investigation on microstrip radiators, with
particular attention paid to improving performance and
miniaturization. Microstrip antennas have enjoyed
proliferate use in many circularly polarized applications due
to their low- proﬁle light weight and useful radiation
characteristics [9]. A circularly polarized EM-wave is
generated when an antenna radiates two orthogonal field
components having equal amplitude with a quadrature phase
difference between them [10],[11]. In practice, circular
polarization can be done with certain methods on the
radiating patch or specialized geometry. There are several
methods to connect the radiating patch to feeder. The
radiating patch can be connected by microstrip line, coaxial
cable, or mutual coupling. Impedance matching is usually
needed between feed line and radiating patch as the input
impedance may differ from characteristics impedance 50 Ω.
Designing a circular polarization antenna is generally much
harder than linear polarization antenna as the bandwidth
where antenna is circularly polarized is so narrow. In this
paper, right hand circular polarized pentagonal microstrip
antenna for GPS technology with the resonance frequencies
at 1.55 GHz and 1.176 GHz is presented.
II. ANTENNA DESIGN
The geometry of the proposed patch antenna is shown in
Figure 1. The design of the antenna is started with
determination of important parameters which directly
influenced the antenna performance. Polygonal geometry is

Design of Dual Frequancy Antenna for Global Positioning System
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159
chosen as the basic configuration which can make the
antenna circularly polarized. Two polygonal microstrip
antennas is developed separately before both of the structure
is joined by feed line. Each of the polygons carries one
resonant frequency to give the combined system a dual
resonant frequency antenna. The results of the desired
antenna of a compact band radiator for use in wireless
communications applications are presented in this section.
Bandwidth is specified as the frequency bandwidth in which
the return loss is less than -10 db. A general model can be
useful in an initial design and usually plays an appreciable
role in antenna scaling. Typically, these models include the
cavity model and the transmission line model for modeling
of microstrip patch antenna. The transmission line analysis
for a microstrip patch antenna is a well-established approach
among the antenna engineers. It is general that increasing
the thickness of the patch antenna will increase the
impedance. However, the thicker the substrate of the
Fig. 1 Actual ADS Model (Top view of Proposed Antenna
Patch)
antenna, the longer the coaxial probe will be used and, thus,
more probe inductance will be introduced [3], which limits
the impedance bandwidth. Consequently, a patch antenna
design that can counteract or reduce the probe inductance
will enlarge the impedance bandwidth.[12] The patch is
supported by a low dielectric substrate with dielectric
permittivity ε with material Rogers Duroid RO4003 as
shown in Table 1. And it is in between patch and ground
plane. The substrate is very thin. The height of the antenna
substrate that is made up of Rogers Duroid RO4003 material
is taken as 1mm. The material Rogers DuroidRO4003 is a
dielectric component defined in the ADS library. It is having
the dielectric constant as 3.38. the substrate height is of
much of importance for the perfect matching of antenna
impedance with the line feed impedance. If a mismatch
occurs then the increase in return loss occurs and return loss
is to be expected as much as less possible for better
performance of antenna. More the return loss, poor the
bandwidth and performance of antenna. The antenna patch
can be made either of copper or gold. Here in this ADS
software copper has been taken by default as the patch
material. Patch material is shown in brown color in the
figure 1 as in the form of polygonal shape. The pattern
seems to be of two pentagons to be joined with a rectangle
strip. Table 1. Showing details about the material. Patch is
of copper material. Substrate is of Rogers Duroid RO4003
material with ε=3.38 the base material is also of copper.
Structure Material
Patch Copper
Substrate Rogers Duroid RO4003
Dielectric Permittivity
(ε)
3.38
Loss tangent 0.0022
Height 1 mm
Table 1. Material Used for Patch Antenna
The near to straight lines which are forming the rectangular
boxes in the patch are the lines which are formed by the
transmission line analysis model executed by the ADS
software.
III. SIMULATION RESULTS
For simulation we used ADS, which is very good
simulator for RF antennas. After simulating the design the
result we got is as follows. The gain of the antenna for GPS
if obtained low, then also the antenna can be used for the aid
application with a purposeful result as if the gain is less
means antennas directivity is less as gain and directly
proportional to each other. The GPS application mainly is a
receiver application as it’s an application which has a
purpose to receive the signals from various users or say
objects.
Fig .2 Radiation Pattern of the antenna
Hence when it’s said that power handling capability of the
microstrip antenna is lower than other antennas, then such a
disadvantage can be neglected on the basis of receiver
application, as it’s an receiver application then it doesn’t
have to transmit power.
So in that case low power handling capability is not an
issue for using microstrip patch antenna for GPS
application. Figure 4. shows the Return Loss (S11) plot of
the design and For the whole range from 1.173GHz to
1.181GHz the Return loss is less than -10 dB and at
frequency 1.176 GHz it’s minimum and the value is -
14.162dB &For the whole range from 1.573GHz to
1.583GHz the Return loss is less than -10 dB and at
frequency 1.575 GHz it’s minimum and the value is –

Design of Dual Frequancy Antenna for Global Positioning System
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160
Fig .3 Parameters of the designed antenna in ADS
20.862dB As seen from the figure 4, the return loss is less
than -10db at frequency 1.176 GHz and 1.575 GHz. This is
a standard level of return loss which can be allowed for any
frequency of operation to be worked upon if it has return
loss less than -10db. The parameters that affect the return
loss are the imperfect impedance matching of the micro strip
line feed and the microstrip patch antenna impedance.
Fig .4 Return Loss (S11) parameter of the antenna
It should be as much as less possible means more negative
the value of return loss as better as the performance. The
bandwidth that is measured at the -10db level of return loss
in the above Figure of return loss versus frequency yields a
band width of 10 MHz and 8 MHz of frequency band for
which the concerned designed antenna is giving same values
of concerned parameter for measuring the performance of
antenna. Figure 2 shows the Radiation Pattern of the design.
The various parameters can be calculated from this
3Dimensional radiation pattern. Figure 3 shows the window
for dual frequency operation for all the Radiation pattern
values for gain, directivity power radiated. Same way
patterns for other frequencies can be generated. At resonant
frequencies of 1.575 GHz and 1.176 GHz, the antenna had
return loss at -20.862 dB and -14.162 dB respectively. The
simulated impedance bandwidths (10dB return loss) are 10
MHz at 1.575 GHz and 8 MHz at 1.176 GHz.
IV CONCLUSION AND FUTURE SCOPES
Microstrip antennas have become a rapidly
growing area of research. Their potential applications are
limitless, because of their light weight, compact size, and
ease of manufacturing. The low profile polygon-shape patch
is presented in this paper. Simulations and results of the
polygonal shape microstrip patch antenna have provided a
useful design for an antenna operating at the dual frequency
of 1.176 GHz & 1.575 GHz for the GPS applications. The
reflection coefficient is below −10dB from 1.173 GHz to
1.181 GHz and 1.573 GHz to 1.583 GHz, at the same time,
the antenna is thin and compact with the use of low
dielectric constant substrate material.
REFERENCES
[1] C.A. Balanis, Antenna Theory, 2nd ed. New York: John
Wiley & Sons, Inc., 1997.
[2] R. Bancroft, Microstrip and Printed Antenna Design,
Prentice Hall of India, 2006
[3] Wi S.H., Kim J.M., Yoo T.H., Lee H.J., Park J.Y., Yook
J.G., Park H.K. Bow-tieshaped meander slot antenna
for 5 GHz application . in Proc. IEEE Int. Symp.
Antenna and Propagation. 2, 456–459,2002
[4] J. R. James, P. S. Hall, and C. Wood, Microstrip
Antenna Theory and Design, Peter Perigrinus, London,
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[5] B. L. Ooi, M.S. Leong, and Q. Shen, "A novel
equivalent circuit for E-shaped slot patch antenna," in
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[6] K. C. Gupta and A. B. Norwood, Microstrip Antenna
Design,Norwood, MA: Artech House, 1988.
[7] X. -X. Zhang and F. Yang, "The study of slit cut on the
microstrip antenna and its applications", Microwave
Opt. Technol. Lett., vol. 18, no. 4, pp. 297-300, Jul.
1998.
[8] Shobhit K. Patel, Y.P.Kosta “E-shape Microstrip Patch
Antenna Design for GPS Application” Institute of
Nirma University, 08-10 Dec, 2011, IEEE.
[9] X. L. Bao and M. J. Ammann, “Dual-Frequency
Circularly-Polarized Patch Antenna With Compact Size
and Small Frequency Ratio,” IEEE Transaction on
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2007.
[10] J. Bahl, P. Bahrtia, Microstrip Antenna, pp. 24, 1982.
[11] B. S. Sullivan, “Design of Circularly Polarized
Omnidirectional Microstrip Sounding Rocket Antennas
for Telemetry and GPS Applications,” University of
Alaska Fairbanks, pp. 7-10, 2001.
[12] Muhammad Fadhli Bukhori, Norbahiah Misran,
Mohammad Tariqul Islam, Mawarni Mohamed Yunus
and Mohammed Nazmus Shakib, Design of Microstrip
Antenna for GPS Application, IEEE International RF
and Microwave Proceedings, Malaysia, pp. 464-466,
Dec 2008.
[13] Bhambhani Priyank Narendra, Microstrip Patch
Antenna Design for GPS Application Using ADS
Software, ICRD-ETS-2013, pp. 111-114, Apr 2013
[6] K. C. Gupta and A. B. Norwood, Microstrip Antenna
Design,Norwood, MA: Artech House, 1988.
[7] X. -X. Zhang and F. Yang, "The study of slit cut on the
microstrip antenna and its applications", Microwave
Opt. Technol. Lett., vol. 18, no. 4, pp. 297-300, Jul.
1998.
[8] Shobhit K. Patel, Y.P.Kosta “E-shape Microstrip Patch
Antenna Design for GPS Application” Institute of
Nirma University, 08-10 Dec, 2011, IEEE.

Design of Dual Frequency Antenna For Global Positioning system

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Design of Dual Frequency Antenna For Global Positioning system