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					         INTERNATIONAL Communication OF ELECTRONICS AND
International Journal of Electronics and JOURNALEngineering & Technology (IJECET), ISSN 0976 –
6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 5, May (2014), pp. 96-104 © IAEME
 COMMUNICATION ENGINEERING & TECHNOLOGY (IJECET)
ISSN 0976 – 6464(Print)
ISSN 0976 – 6472(Online)
Volume 5, Issue 5, May (2014), pp. 96-104
                                                                               IJECET
© IAEME: www.iaeme.com/ijecet.asp
Journal Impact Factor (2014): 7.2836 (Calculated by GISI)
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                                                                              ©IAEME



        STACKED LAYER CONFIGURATION OF MICRO STRIP PATCH
            ANTENNA WITH DIFFERENT SHAPES OF PATCHES

                          Arivumani Samson .S1, Sankar .K2,        Bargavi .R3
                         1
                            Asst.Prof, Dept. of ECE Engg., Arunai Engg College.,
                         Velu Nagar, Mathur, Tiruvannamalai-606603, Tamilnadu
                       2,3
                           PG Scholar., Dept. of ECE Engg., Arunai Engg College.,
                        Velu Nagar, Mathur, Tiruvannamalai-606603, Tamilnadu.




ABSTRACT

        This paper intends to overcome the limitations of the Microstrip Patch antenna’s with the
stacked approach design for UWB applications. With the known advantages and Limitations and
with availability of sophisticated software tools the Patch remains as the attraction of the researchers
in the recent era. The development of a rigorous design is necessary for realizing compact and
efficient antennas in the wireless applications. Also, it is important that these antennas should
maintain acceptable performance characteristics, such as impedance bandwidth, gain, return loss and
high efficiency throughout a single or multiple frequency bands and standards. In this paper the
proposed antenna is designed to minimize the physical size without sacrificing the above mentioned
performance characteristics of the antenna. This is achieved by stacked layer configuration of two
patches. The patch is etched by different shapes of alphabetical E & U to improve the bandwidth. In
the proposed antenna each patch having the dimension of 24mm x 24mm and the thickness of the
lower substrate is 0.3mm is used. Air gap between upper and lower patch is 0.2mm. Totally the
thickness of the antenna is 0.5mm. Two Different configurations by varying the positions of E and U
Slot is proposed and analyzed. The results of the configuration is compared and tabulated. The
configuration with E as upper and U slot Patch as lower patch is considered as the best as it provides
dual band with improved Bandwidth. The impedance bandwidth of the proposed structure is 1.3 GHz
and at 5.06GHz and 1.1GHz at 7GHz center frequency. Gain of the antenna is 7.5 db at 5GHz and db
at 7GHz. The VSWR of the antenna is <2. Design and analysis of the antenna is carried out with the
HFSS tool.

Keywords: Bandwidth, E-Shape, Gain, Stacked Layer, U-Shape.



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International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –
6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 5, May (2014), pp. 96-104 © IAEME

I. INTRODUCTION

         Recently Microstrip patch antennas are widely used often in antenna designs for their
simplicity and compatibility the primary barrier to implementing these antennas in many applications
is their limited bandwidth, low efficiency and low gain. Over the years, a number of researches and
tests have been carried out to increase both bandwidth and radiation efficiency [1]. One of the
important proposals involved in improving bandwidth is to increase heights by stacking radiating
patch elements with probe feed. Also, arranging the radiating elements in one or two dimensionally
will increase gain of Microstrip patch antennas [1]. The main goal of this paper is to overcome the
disadvantages such as low gain and narrow bandwidth and also try to reduce the overall size of the
patch antenna.
         Microstrip antennas can be fed directly by Microstrip line or coaxial probe, and it can be
excited using apertures on ground plane by coupling, which there is no physical contact with the
radiating element. The efficiency of antenna depends on power to the radiating element that feeding
technique is very important. Consequently, the feeding techniques have significant impact on the
power to the radiating element that determines the efficiency of the antenna [2].
         Coaxial probe feed techniques are arranged by soldering coaxial connector to the patch where
Inner conductor is connected to patch and outer conductor to the ground plane. This technique is
shown in Fig. 1. The main advantages of coaxial probe feeding are also easy to fabricate, match input
impedance, and its low spurious radiation [2].




                                  Fig. 1: Coaxial Feed Technique

        Small size wideband Microstrip patch antenna with slot in ground plane and stacked patch
fed through Microstrip line is presented. By inserting slot on ground plane and stacked patch
supported by wall, the bandwidth can improve up to 25% without significant change in the frequency
[7]. A reduced ground plane structure and a stacking of unequal E-shape patch is investigated for
enhancing the impedance bandwidth on the substrate Duroid 5880 in [8]. Simulations and results of
the stacked unequal E-shape patch with partial grounding have been provided a useful design for an
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International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –
6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 5, May (2014), pp. 96-104 © IAEME

antenna operating at the frequency of 2-2.29 GHz for WLAN and 3.53-4.58 GHz for Wi-Max
applications. The return loss of the proposed antenna is less than -10 dB and the increase in
bandwidth in comparison to the unequal E-shape patch antenna with stacked unequal e-shape patch
antenna with partial grounding is 17.6%[8].
        The paper has been organized as follows: section 2 describes the design procedure of the
stacked patch. Section 3 explains the results obtained through HFSS. Sections 4 concludes and lists
the future work.

II. DESIGN PROCEDURE

        The radiation characteristics of a patch antenna is determined by the thickness and type of
substrate used. The impedance bandwidth and efficiency (η) of a patch antenna varies inversely to
one another. The parameters of dielectric constant (εr) and thickness (h) can be varied to obtain
different η, which will ultimately increase impedance bandwidth [1]. Thick substrates with high
dielectric substrates would result negatively on the radiation efficiency. By stacking a parasitic patch
close to the fed patch widens bandwidth, two different shaped patches have two resonant frequencies
near to each other and the wide bandwidth is obtained [4]. Bandwidth requirement can be met by
selecting appropriate thickness of substrate and dimension of patch. the proposed antenna the stacked
layer is designed as shown in figure 2.




                                   Fig. 2: Proposed antenna design.

        This paper intends to design a stacked layer configuration of Microstrip patch antenna with
different shapes of slots on the patch. The antenna consists of a two rectangular patches having the
dimension of 20mmX20mm. one patch is placed on dielectric Rogers RT/ Duroid 5880(tm) with the
thickness of 0.3mm and the dielectric constant is 2.2 and another one patch is placed on air substrate
with the thickness of 0.2mm and the dielectric constant is nearly 1. To enhance the bandwidth of the
antenna we can increase the thickness of the air gap. When we increase the gap between two patches
the electromagnetic coupling can be increased so that the bandwidth of the antenna increased but
here the size of the antenna is an important consideration. The proposed antenna’s overall height is
0.5mm and the dimension of the substrate is 60mm X 40mm thus the size of the patch antenna is
minimized as possible with an efficient result. In this stacked layer configuration the upper patch act
as parasitic patch and lower patch act as fed patch.

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International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –
6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 5, May (2014), pp. 96-104 © IAEME




                                        Fig. 3: E-Shape patch




                                        Fig. 4: U-Shape patch

   Another one important consideration in the design of Microstrip patch antenna is location of feed.
Different location of the feed can produce different output for different configuration of the patch we
analyze the different feed location to get maximum possible output. The proposed antenna having
feed location of (1,-0.75) the radius of coax cable is 0.16mm and the conductor used for coaxial pin
is PEC.
   In the proposed antenna, one patch is cut by E-shape as shown in fig. 3 and U-shape slot is put on
another one patch as shown in fig. 4. The E-shape patch and U-shape slotted patch are analyzed and
simulated separately and they are combined with each other as stacked layer configuration to
improve the performance of the patch antenna. In the stacked layer two configurations are
established and compared. One configuration is obtained by placing E-shape patch as lower patch
and U-shape slotted patch as upper patch and another configuration is obtained by replacing the two
patches. The simulation results and comparison of the results are shown in section III.

III. OUTPUT SIMULATION AND COMPARISON

        The analysis section demonstrates the analysis of antenna parameters such as radiation
pattern, return loss, VSWR, etc. in this paper gain of the antenna and return loss along with

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International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –
6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 5, May (2014), pp. 96-104 © IAEME

Bandwidth. The gain of the antenna can be measured by obtaining the radiation pattern of the
antenna for Φ=0 deg. and Φ=90 deg. for a particular frequency. The proposed antenna consists of
two configurations. We analyzed each configuration separately. First we simulate the stack with E-
shape as lower patch and U-shape as upper patch slot. The design model in HFSS is shown in fig.5.




       Fig. 5: Stacked Patch with U slotted as upper patch and E-shaped patch as lower patch

        The radiation pattern is of the antenna shown in fig. 5 is shown in fig. 6. The gain of this
antenna is nearly 6 dBi at the operating frequency of 5GHz. From the return loss curve, impedance
bandwidth of the antenna can be measured. From the fig.7 the bandwidth of the antenna shown in
fig. 5 is measured as 735MHz with the centre frequency of 4.53GHz. so the we can get 16.2% of
impedance bandwidth. And the return loss of the antenna is nearly -37 dB. Another important
parameter in the design of the antenna is VSWR. In an efficient antenna design the VSWR must be
less than 2. Proposed antenna having the VSWR of 1.83 shown in fig. 8.




                       Fig. 6: Radiation pattern for an antenna shown in fig. 5
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International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –
6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 5, May (2014), pp. 96-104 © IAEME




                      Fig. 7: Return loss curve for the antenna shown in fig.5




                         Fig. 8: VSWR plot for the antenna shown in fig.5

       The next configuration of the proposed antenna is upper patch consist of E-shape patch and
the lower patch is cut by U-shape slot. As shown in fig. 9.




    Fig. 9: Stacked Patch with E-shaped patch as upper patch and U slotted patch as lower patch

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International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –
6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 5, May (2014), pp. 96-104 © IAEME

       The radiation pattern is of the antenna shown in fig. 9 is shown in fig. 10. The gain of this
antenna is nearly 7.5 dBi at the operating frequency of 5GHz.




               Fig: 10: Radiation pattern of the antenna configuration shown in fig. 9

        The return loss curve is shown in fig. 11. From the return loss curve, impedance bandwidth of
the antenna can be measured. In this configuration we get dual band with two center frequencies are
5GHz and 7GHz. At the first band the return loss -15dB and at the second band the return loss is -
13dB. The bandwidth of the frequency band having the center frequency 5GHz is 1.4GHz which is
28% of center frequency and the bandwidth of the band having the center frequency 7GHz is 1.1GHz
which is 15.7% of the center frequency. This antenna configuration, also having the VSWR of 1.83.
The VSWR plot is shown in fig. 12.




              Fig. 11: Return loss curve for the antenna configuration shown in fig. 9.

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International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 –
6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 5, May (2014), pp. 96-104 © IAEME




              Fig. 12: VSWR Vs Frequency plot for the configuration shown in fig. 9.

                  TABLE I: Comparison of the performance of proposed antennas
                      Configuration Shown in Fig.5 Shown in Fig.9
                           Band            Single            Dual
                          Center
                                          4.5GHz       5GHz 7GHz
                        Frequency
                       Band width          16.2%        28% 15.7%
                       Return loss         -37dB       -15dB -13dB
                           Gain             6dBi        7dBi     7dBi
                          VSWR              1.83        1.83     1.83


IV.    CONCLUSION

        In this paper two successful compact stacked antenna designs have been introduced to the
wireless and radio frequency design community. The first one provides single band at frequency
4.5GHz and having the bandwidth of 16.2% of the centre frequency and the return loss is -37dB. The
gain is 6dBi. The next one provides dual band at the frequencies 5GHz and 7GHz. The bandwidth of
this band is 28% and 15.7% with respect to the centre frequencies. The return loss is -15 dB and -
13dB at the centre frequency. The VSWR of both configurations is 1.83. The dimension of both
patches is 24mmX24mm. The thickness of the antenna is 0.5mm. In future, we intend to extend the
above slotted stack design with meta material substrate with different slot shapes to improve the
Broadband performance of the Patch Antenna.

V. REFERENCES

 [1]   R. GARG, P. BHARTIA, I. BAHL, AND A. ITTIPIBOON, MICROSTRIP ANTENNA DESIGN
       HANDBOOK, 2ND ED.NORWOOD, MA: ARTECH HOUSE, 2001.
 [2]   C. A. Balanis, Antenna Theory, 3rd ed. Hoboken, NJ: John Wiley & Sons, 2005
 [3]   D. M. Pozar, Microwave Engineering, 3rd ed. Hoboken, NJ: John Wiley & Sons, 2005.
 [4]   E. Nishiyama, M. Aikawa, and S. Egashira, “Three-element stacked microstrip antenna with
       wide-band and high-gain performances,” in IEEE Antennas and Propagat. Society Int.Symp.,
       vol. 2, U.S.A., Jun. 2003, pp. 900-903.
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 [5]    R.Azaro, E. Zeni, P. Rocca, and A.Massa, Synthesis of a Galileo and Wi-max three-band,
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 [6]    R.Chair, C. Mak, K. Lee, K. Luk, and A. A. Kishk, Miniature wideband half U-slot and
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 [7]    H. F. AbuTarboush, H. S. Al-Raweshidy and R. Nilavalan, “Bandwidth Enhancement for
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 [8]    R.Divya, M.Priya, “Design and Characterization of E-Shape Microstrip Patch Antenna for
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 [9]    J. Anguera, C. Puente, and C. Borja, “A procedure to design stacked microstrip patch antenna
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 [10]   D. K. Srivastava, J. P. Saini, and D. S. Chauhan, “Broadband Stacked H-shaped Patch
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 [12]   Jagadeesha.S, Vani R.M and P.V Hunugund, “Stacked Plus Shape Fractal Antenna for
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 [13]   L. Lolit Kumar Singh, Bhaskar Gupta and Partha P Sarkar, “A Review on Effects of Finite
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