Ijecet 06 09_009

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International Journal of Electronics and Communication Engineering & Technology
(IJECET)
Volume 6, Issue 9, Sep 2015, pp. 75-81, Article ID: IJECET_06_09_009
Available online at
http://www.iaeme.com/IJECETissues.asp?JType=IJECET&VType=6&IType=9
ISSN Print: 0976-6464 and ISSN Online: 0976-6472
© IAEME Publication
DUAL BAND COMPACT MICROSTRIP
PATCH ANTENNA WITH DEFECTED
GROUND STRUCTURE
Rashmi A. Pandhare
Department of Electronics Engineering,
Datta Meghe Institute of Engineering, Technology & Research, Wardha (India)
Prasanna L. Zade
Department of Electronics & Telecommunication Engineering,
Yeshwantrao Chavan College of Engineering, Nagpur (India)
ABSTRACT
In this paper, a compact dual band rectangular microstrip patch antenna
is proposed with the defects integrated in metallic ground plane. Initially a
regular rectangular shape patch antenna is designed which resonates at 5.2
GHz. With the introduction of DGS in the metallic ground plane, the
microstrip antenna is found to be resonant at 3.5 GHz and 5.2 GHz
simultaneously, suitable for WiMAX and WLAN application. Thus the
proposed antenna behaves as a compact as well as dual frequency band
operated antenna. The antenna was fabricated with the RT-Duriod substrate
with dielectric constant of 2.2 and height of 0.762mm. This technique is
validated experimentally and measured results were in good agreement with
simulated results.
Key words: Microstrip Patch Antenna, Defected Ground Structure (DGS),
Dual Band, WiMAX, WLAN.
Cite this Article: Rashmi A. Pandhare and Prasanna L. Zade. Dual Band
Compact Microstrip Patch Antenna with Defected Ground Structure,
International Journal of Electronics and Communication Engineering &
Technology, 6(9), 2015, pp. 75-81.
http://www.iaeme.com/IJECET/issues.asp?JType=IJECET&VType=6&IType=
9
1. INTRODUCTION
Dual-band antennas are of the interest for wireless communication system that use
two band of frequencies, such as WLAN and WiMax, because they could substitute
for two individual antennas. In addition, the miniaturization of antennas also became
more important due to the increasing demand of small antennas as the rapid

2. Rashmi A. Pandhare and Prasanna L. Zade
http://www.iaeme.com/IJECET/index.asp 76 editor@iaeme.com
development in wireless communications. Both of this techniques reduce the size,
cost, and complexity. Microstrip antenna used widely in wireless communication due
to their light weight, low profile, low cost, ease of fabrication and cost effective.
Efforts are made to design compact microstrip antenna with higher percentage of
miniturization, as the demand of small size antennas at low frequency have drawn
much intrest from reaserchers[1]. Many efforts have been made in order to achieve
the size reduction such as using a dielectric substrate of high permittivity [4],
Defected Microstrip Structure (DMS) [5], PBG etched on grounded substrate turned
to limited numbers of defects, commonly known as a defected ground structure
(DGS) [6],or a combination of them. Due to this techniques various effects in the
microstrip antenna were observed which make the antenna operate at lower frequency
band. Similarly many techniques have been reported for designing low cost,small
profile and efficient dual band antenna. Some techniques used a patch antenna at
higher order mode that has a quasi-similar radiation pattern of the fundamental mode.
Parasitic element in the proximity of the radiating element, multi radiating elements ,
stub attached to the radiating element [9]. Microstrip antenna with DGS can also
support this purpose with multiband that can operate at different frequencies for one
device[2].
In this paper, a dual band compact microstrip patch antenna is proposed. Initially
the proposed antenna resonates at 5.2 GHz and then by integration of two defects in
ground plane, the microstrip rectangular patch antenna is made to resonant at 3.5 GHz
and 5.2 GHz simultaneously, suitable for two multiband wireless communication
system such as the wireless local area network (WLAN) 2.4/5.2/5.8 GHz and the
worldwide interoperability for microwave access (WiMAX) 3.5/5.5GHz [12]. Thus a
dual band compact antenna with the size reduction of 50% compared with the
conventional one is carried out.
2. MICROSTRIP PATCH ANTENNA WITHOUT DGS
The proposed rectangular microstrip patch antenna is shown in Fig.1. In this design,
the substrate RT Duroid was used due to its advantages. The substrate height was
0.762 mm with dielectric constant of 2.2 and the loss tangent 0.0004. The dimensions
of antenna were optimized by using CST Microwave Studio tool. On the top of the
substrate, a metal patch with dimension Lp =18.6 mm and Wp =22.80 was connected
to 50 ohm feed line with an insect. The dimension of insect feed were Li=11mm and
Wi=2.3 mm. The simulation result of reference antenna is shown in Fig. 2 and the
radiation pattern is as shown in Fig.3
Figure 1 Reference rectangular patch antenna without DGS frequency

3. Dual Band Compact Microstrip Patch Antenna with Defected Ground Structure
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Figure 2 Simulated S11 versus frequency indicating fundamental resonant
Figure 3 Radiation pattern without DGS at 5.2GHz
The design and simulation of the reference antenna has been carried out using full
wave EM simulator CST Microwave Studio. Fig.2 shows [S11] dB of the antenna
without any DGS in ground plane resonates at 5.2 GHz at -16.53 dB with the gain
5.86 dBi.
3. COMPACT DUAL BAND ANTENNA DESIGN
The detail structured of proposed compact dual band antenna is shown in Fig.4. Two
identical swastika shaped DGS with one slot are introduced in ground plane. Fig.5
shows the detail geometry of etched DGS with the specified dimensions.
4(a) 4(b)
Figure 4 (a) Front view of Antenna (b) Back view of antenna with etched DGS

4. Rashmi A. Pandhare and Prasanna L. Zade
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Figure 5 DGS Geometry (A=8mm, B=8mm, C=3.5mm, D=4mm, E=1mm, Di=4mm)
DGS is introduced on the metallic ground plane of microstrip patch antenna. Both
defective ground structures are positioned at an optimal position with respect to each
other, so that the effect of mutual coupling is minimized among the two defects [2].
As the defect geometry etched in the ground plane disturbs its current distribution
[11], this disturbance affects the transmission line characteristics, such as the line
capacitance and inductance. In other words, introducing DGS in a microstrip antenna
can result in an increase of the effective capacitance and inductance [8] which
influences the input impedance and current flow of the antenna and thus reducing its
size [6]with respect to a given resonance frequency. The return loss of the regular
rectangular patch shape antenna with DGS is shown in the Fig.6 and radiation pattern
is as shown in Fig.7.
Figure 6 Simulated S11versus frequency indicating resonant at 3.5GHz and 5.2GHz
simultaneously
Figure 7 Radiation pattern with DGS

5. Dual Band Compact Microstrip Patch Antenna with Defected Ground Structure
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It is observed that when DGS is introduced in a ground plane the microstrip
antenna is simultaneously resonant at 3.5 GHz, and 5.2 GHz. The simulation result
gives a return loss of -33 dB at the resonance frequency around 3.5 GHz and return
loss of -15 dB at the resonance frequency 5.2 GHz with the gain 4.96 dBi. Thus
miniaturization about 50% was obtained along with the dual frequency band operation
of microstrip patch antenna using DGS.
4. FABRICATION AND MEASUREMENT
A prototype of designed microstrip patch antenna without DGS and with DGS was
fabricated as reference antenna and proposed antenna respectively. RT-Duroid
substrate with relative dielectric constant 2.2 and the thickness 0.762 mm was used.
Fig. 8 shows the size of regular rectangular microstrip patch antenna without DGS.
Fig.9 (a) and (b) shows size of the top and back view respectively of regular
rectangular microstrip patch antenna with DGS.
Figure 8 Prototype of the fabricated rectangular microstrip patch antenna without DGS
9(a) 9(b)
Figure 9 Prototype of the fabricated (a) rectangular microstrip patch antenna with DGS (b)
Back view with etched DGS
In order to measure the various parameters of the antenna we have been
employing MS2028C vector network analyzer, with frequency range is limited to 20
GHz. Thus S11 parameter was measured and compared to the simulated result. Fig.10
shows the comparison between measured and simulated results of regular rectangular
microstrip patch antenna with DGS resonating at 3.5 GHz and 5.2 GHz
simultaneously.

6. Rashmi A. Pandhare and Prasanna L. Zade
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Figure 10 Simulated and Measured S11versus frequency indicating resonant at 3.5GHz and
5.2GHz simultaneously
Experiment shows an excellent agreement of the measured result with simulated
result.
5. CONCLUSION
The two swastika shaped with one slot defective ground structure are integrated in the
rectangular microstrip antenna which result in size miniaturization of about 50%
along with the dual band operation of microstrip antenna. The resonance frequency of
the initial antenna without DGS is 5.2 GHz at -16.53 dB with the gain 5.86 dBi,
whereas with DGS, the resonance frequency at 5.2 GHz at -15dB and 3.5 GHz at -
33dB simultaneously with gain 4.96 dBi suitable for two multiband operation WLAN
(2.4/5.2/5.8GHz) and WiMAX (3.5/5.5GHz). In this way we have been able to reduce
the antenna size up to 50% with dual band operation as compared to conventional
antenna without much degrading the antenna performance.
ACKNOWLEDGMENT
The authors would like to thank the Centre of Applied Research, IIT, New Delhi for
the support in carrying out design, experimentation and fabrication of antenna.
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