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A dual-band design of a finite ground coplanarwaveguide (CPW) fed antenna is presented for simultaneouslywireless local area network (WLAN) and worldwideinteroperability for Microwave Access (WiMAX) applications.
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Design of Double L-Slot Microstrip Patch Antenna for WiMAX and WLAN Application
R. Jothi Chitra, Dept. of ECE
Adhiparasakthi Engineering College, Melmaruvathur. Chennai, India
B. Ramesh Karthik Dept. of ECE
Adhiparasakthi Engineering College, Melmaruvathur. Chennai, India
V. Nagarajan Dept. of ECE
Adhiparasakthi Engineering College, Melmaruvathur. Chennai, India
Abstract— A dual-band design of a finite ground coplanar waveguide (CPW) fed antenna is presented for simultaneously wireless local area network (WLAN) and worldwide interoperability for Microwave Access (WiMAX) applications. The proposed antenna, comprising a rectangular planar patch element embedded with two L shaped slots. The simulated -10 dBi bandwidth for return loss is from 2 to 6 GHz, covering some of the WiMAX and WLAN bands. The parametric study is performed to understand the characteristics of the proposed antenna. Also, good antenna performances such as radiation patterns and antenna gains over the operating bands have been observed and simulated peak gain of the antenna is 7.68 dBi at 2.8 GHz and maximum return loss is obtained is -35 dBi at 4.8GHz.
Keywords- Double L-Slot Microstrip antenna; Dual band antenna; Patch antenna; Slot antenna.
I. INTRODUCTION
In this rapid changing world in wireless communication
systems, multiband antenna has been playing a very important
role for wireless service requirements. Wireless local area
network (WLAN) and Worldwide Interoperability for
Microwave Access (WiMAX) have been widely applied in
mobile devices such as handheld computers and intelligent
phones. These two techniques have been widely considered as
a cost-effective, viable, and high-speed data connectivity
solution, enabling user mobility.
Using Microwave applications, slot antennas fed by
coplanar waveguide (CPW) lines are receiving increasing
attention [1]. Numerous advantages have been obtained by
feeding a radiating element with coplanar waveguide feeds;
such as lower radiation leakage and less dispersion than
microstrip lines. This type of structure has been modeled as a
radiating element and is referred to as a CPW-fed slot line
monopole antenna.
A Modular antenna dual-band design of a finite ground
coplanar waveguide (CPW)-fed monopole antenna is
presented for simultaneously satisfying wireless local area
network (WLAN) and worldwide interoperability for
Microwave Access (WiMAX) applications [2-5]. The Modular
antenna, comprising a rectangular planar patch element
embedded with double L shaped slots in the patch element [2].
Prototypes of the obtained optimized antenna have been
designed and constructed. The parametric study is performed
to understand the characteristics of the Modular antenna.
II. ANTENNA MODEL
The geometry of the proposed finite ground coplanar waveguide (CPW) fed dual-band antenna is shown in Fig. 1. The proposed antenna was fabricated on FR4 substrate with dielectric constant is 4.4 and thickness 1.6 mm. The basis of the antenna structure is chosen to be a rectangular patch element with dimensions of width W and length L, and with a vertical spacing of ‘d’ away from the ground plane. A conventional CPW fed line designed with a fixed signal strip thickness Wf and a gap distance of ‘g’ between the signal strip and the coplanar ground plane is used for exciting the radiating patch element.
Figure 1. Dimensions of proposed antenna.
Two finite ground planes with the same size of width Wg
and length Lg, are situated symmetrically on each side of the CPW feeding line [2]. Patch, ground length and width are calculated by using transmission line model. The relative dielectric constant ( r) [6 ,7] of the substrate is given as
r rr
1 1 1
2 21 12
HW
ε εε −
� �� ��
= ++
�
+ (1)
A very popular and practical approximation relation for normalized extension of the length [6,7] is obtained from below equation
r
eff
( 0.3) 0.2
( 0.2
64
0.412
858)
WH
LWH
ε
ε
� �+ � +Δ =
�� �
�− + �� �� �
(2)
The effective length of the patch is expressed as
eff 2L L L= + Δ (3)
Formula for Patch width [6 ,7] is given by
0 r 1
22W
λ ε += (4)
Length is given as
r 0 0
1
2 eff
Lf ε μ ε
= (5)
The final optimized dimensions of proposed antenna are length of the rectangular patch L=19.3mm, width of the rectangular patch W=19.27mm, width of ground plane GW=10.2 mm, length of ground plane GL=16.2 mm. Slot length are L1=5.7mm, L2=7.5mm and having width of Ws=1mm. Length of the feeding FL = 19.2mm and Feed width is FW =3mm.
The space between the rectangular patch and ground plane G = 3mm and the feed line width of the feeding port is Wf = 3mm and vertical spacing between feed-line and ground plane d=1mm. The optimum parameters are obtained with the aid of Ansoft HFSS software listed in Table I.
III. SIMULATION RESULTS
The simulation results for return loss for the frequency
range from 2 to 6 GHz are shown in the Fig. 2. It can cover
the 5.15–5.35GHz WLAN band and 3.4–3.69 GHz WiMAX
band of wireless communication system.
The most common case for measuring and examining
VSWR is when installing and tuning transmitting antennas.
Ideally, the VSWR must lie in the range of 1-2 which is
achieved in Fig. 3 for the 2 to 6 GHz frequency range.
The simulation results for gain for the frequency range from
2 to 6 GHz are shown in the Fig. 4.
TABLE I. GEOMENTRY OF PROPOSED ANTENNA
Parameter Value (in mm )
L1 5.7
L2 7.5
W 19.27
L 19.3
GL 16.2
GW 10.5
SL 40
SW 26
G 3
D 1
FL 19.2
FW 3
Figure 2. Return Loss versus Frequency
Figure 3. VSWR Versus Frequency Plot
Ret
urn
Loss
(d
bi)
Frequency (GHz)
VS
WR
Frequency (GHz)
Figure 4. Gain versus Frequency Plot.
Figure 5. Radiation pattern in Azimuthal Plane
Figure 6. 3-Dimensional Rational pattern.
The simulation results for impedance for the frequency
range from 2 to 6 GHz and the impedance is perfectly matched
to 50�. The simulated radiation patterns of the proposed
CPW-fed monopole antenna are presented in Fig. 5 and 3D
radiation pattern is shown in Fig. 6.
The 3D current distribution plot gives the relationship between the co-polarization (desired) and cross-polarization (undesired) components. The surface currents mainly flow along the lower edges of patch and along the signal strip line is shown in Fig. 7.
Figure 7. Current Distribution
The simulated impedance bandwidth of the proposed antenna covers two impedance bandwidths, 3.34 to 4.056 GHz as the lower band and 4.736 to 5.432 GHz as the upper band, respectively. It can cover the 5.15–5.35 GHz WLAN band, and 3.4–3.69 GHz WiMAX band of wireless communication system. The radiation pattern obtained in the x-y plane is nearly Omni-directional, and that in the elevation plane is similar to monopole kind of antenna. Radiation performance of the antenna is acceptable at all the frequency bands.
Frequency(GHz)
Gai
n(d
bi)
IV. CONCLUSION
The purpose of this work is successfully completed as
studied and designed the antenna using a CPW-fed Dual band
Double L slot antenna. The simulated result of the return loss
of the CPW-fed Microstrip patch antenna yields dual band.
The radiation pattern is unidirectional pattern for all of
operation bandwidth, although the main lobe at the end of
operation frequency shows a little bit lifting. It can be
observed that the peak gain can be higher than 5 dBi at
3.5 GHz.
The simulation gave results good enough to satisfy our
requirements to fabricate it on hardware which can be used
wherever needed. The investigation has been limited mostly to
theoretical studies and simulations due to lack of fabrication
facilities. Detailed experimental studies can be taken up at a
later stage to design the array antenna.
REFERENCES
[1] Yen-Liang Kuo and Kin-Lu Wong , “Printed Double-T Monopole Antenna for 2.4/5.2 GHzDual-Band WLAN Operations”, IEEETransaction on Antenna and Wireless Propagation, VOL. 51, NO. 9, September 2003.
[2] Liu, W.C, “Broadband dual-frequency cross-shaped slot CPW-fed monopole antenna for WLAN operation”. Microwave Optical Technol. Letters, vol. 46, 2004, p.353–355J. Clerk Maxwell, A Treatise on Electricity and Magnetism, 3rd ed., vol. 2. Oxford: Clarendon, 1892, pp.68–73.
[3] Horng-Dean Chen, Jin-Sen Chen and Yuan-Tung Cheng, “Modified inverted-L monopole antenna for 2.4-5 GHz dual-band operations”, Electronics letters 30th October 2003 Vol. 39 No. 22.
[4] Cheg-Tse Lee and kin-Lu Wong, “Uniplanar Printed Coupled-Fed PIFA With a Band-Notching Slit for WLAN/WiMAX Operation in the Laptop Computer”, IEEE Transaction on Antenna and Wireless Propagation letters, VOL. 57, NO. 4, April 2009.
[5] Shu Yan and Qing Zhang, Dept of Telecommunication Engineering, Jiangsu Universty, "A Novel Dual- Frequency and Dual-polarized Microstrip Antenna array for wireless sensor networks GPRS module of Cluster Nodes"International Conference on Intelligent Computing and Intelligent Systems, 2009. ICIS 2009.
[6] C. A. Balanis, “ Antenna Theory, Analysis and Design”, JOHN WILEY & SONS,INC, New York 1997.
[7] R. Garg, P. Bhartia, I. Bahl, A. Ittipiboon, “Microstrip Antenna Design Handbook”,ARTECH HOUSE, Boston 2001.