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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459, Volume 1, Issue 2, December 2011)

17

A Compact Planar Multiband Antenna For WLAN: Design,

Simulation and Results

Akhilesh Kumar

1

, Charu Tyagi

2

, Rekha Rani

3

, Ritika Tripathi

4

1Depatrment of Electronics & Communication, Rajkumar Goel Institute of Technology For Women ,U.P.(India)

1akhilesh48@gmail.com

2Charutyagi24@rediffmail.com

Abstract-- With the rapid development of wireless communication systems, the multiple separated frequency bands antenna has become one of the most important circuit elements and attracted much interest. In order to satisfy the IEEE 802.11 WLAN standards in the 2.4 GHz (2400–2484 MHz)/5.2 GHz (5150–5350 MHz)/5.8 GHz (5725–5825 MHz) operating bands and the worldwide interoperability for microwave access (WiMAX) 2.5/3.5/5.5 GHz (2500–2690/3400–3690/5250–5850 MHz) bands, various antennas for wide band operation have been studied for communication and radar systems. The design achieves a good input impedance match and linear phase of S11 throughout the pass band (1.5–7 GHz and-10 dB criterion for impedance bandwidth). Various bands are 1.96 GHz, 3 GHz, 5GHz. The gain of the antenna at resonant frequencies is >4.6 dBi. The maximum directivity of the antenna is 8.5dBi and the VSWR is between 1 and 2. The bandwidth of the antenna is 200 MHz, 1100 MHz, 2030 GHz bands respectively. This antenna is suitable for applications in ICMS, DECT, UMTS, Bluetooth and WLAN systems. Because of linear phase and good impedance match, with some further optimization and manufacturing aspect, this antenna can serve in UWB and wireless USB applications.

Keywords—multiband antenna, monopole antenna, WLAN, U slot antenna, WiMAX , Triangular Patch, CPW Feed.

I.

I

NTRODUCTION

The current upsurge in wireless communication systems has forced antenna engineering to face new challenges, which include the need for small-size, high-performance, low-cost antennas.

In order to satisfy the IEEE 802.11 WLAN standards in the 2.4 GHz (2400–2484 MHz)/5.2 GHz (5150–5350 MHz)/5.8 GHz (5725–5825 MHz) operating bands and the worldwide interoperability for microwave access (WiMAX) 2.5/3.5/5.5 GHz(2500-2690/3400-3690/5250-5850 MHz) bands, multi-band antennas with low cost, compact size, easy fabrication and higher performance are required. Several dual-band antennas for WLAN applications were presented [1]–[5]. However, none of the above available designs can achieve a dual-band response with sufficiently large bandwidth to additionally cover the whole WiMax bands.

(2)

International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459, Volume 1, Issue 2, December 2011)

18 A multiband-wideband assembled monopole antenna with a small size is presented in this communication. The proposed antenna can generate four resonant frequencies which are formed into three wide bands centered at about 1.96 GHz, 3.04 GHz and 5 GHz to cover all the 1.9/2.4/5.2/5.8 GHz GPS & WLAN operating bands and the 2.5/3.5/5.5 WiMAX bands. With multi-wideband operation achieved in this design, the assembled monopole antenna requires a small size of 30 X 50mm2. The antenna also shows good dipole-like radiation characteristics with small cross-polarization level and moderate gain over the operating bands, which is attractive for practical application in the WLAN/WiMAX communication gadgets.

II.

PROPOSED

ANTENNA

DESIGN

The geometry of the proposed monopole antenna is shown in Figure.1.The antenna is formed by an equilateral triangular monopole and a modified U-shaped and rectangular monopole, and is fed by a CPW microstrip feed line. In order to get a compact antenna size for the design, the U-shaped and rectangular monopole is placed outside the triangular monopole.

The dual-band performance of the proposed antenna is obtained from the dual resonant monopoles of different dimensions. In the geometry, the resonant path length ( L11= S + L3 + L1 )and (L22 = S + L4 + L2) of the U-shaped , rectangular monopole and the triangular monopole are set close to quarter-wavelength at the their fundamental resonant frequencies, and can be calculated from the following equations:

L11 = c / 4 f1 √ εre --- (1)

L22 = c / 4 f2 √ εre ----(2)

εre = (εr+1) / 2 ----(3)

where c is the speed of light, εre is the relative

permittivity of the substrate, f1 and f2 denote the fundamental resonant frequencies of the U-shaped and square shaped monopole and triangular monopole respectively.

However, the design (1) to (3) are only suitable for the single rectangular ,U-shaped monopole or the triangular monopole, without considering the mutual coupling between the monopoles.

Therefore, the initial antenna design is provided by these design equations. Furthermore, accurate design for the proposed antenna need to be adjusted and optimized using electromagnetic simulation software (such as IE3D). To excite the antenna, a 50-CPW transmission line, having a signal strip of width W1 and a gap of g distance between the signal strip and the side plane, is used. The proposed antenna geometry is placed on finite ground plane of 50 X 50 mm . To enhance the antenna parameters a rectangular slots of 12 x 8 mm is cut on the opposite edges of the ground plane as shown in figure 2.

[image:2.612.339.550.440.630.2]

The design of the proposed antenna follows the described guidelines followed by the optimization with the software IE3D. In the design, the antenna is printed on a 1.6 mm thick FR4 substrate of dielectric constant 4.4 and loss tangent 0.0245. The rectangular proximity patch and annular slot is employed to generate the first mode at 1.9 GHz , U-shaped monopole is employed to generate the first resonant mode at about 2.5 GHz for lower band operation, while the triangular monopole is employed to create a fundamental mode at about 3.6 GHz for upper band operation. Values of the design parameters shown in Figure. 1 and Figure 2. calculated using the presented method and optimized using IE3D are L=15 mm, L1=19 mm L2=16 mm , L3 = 12 mm , L4= 6.5 mm, L5= 35 mm , W= 12mm , W1= 3mm, W2=1.5mm, W3= 8mm, P1= 9mm, P2 = 9mm, S =1.5mm, g = 0.5 mm .

(3)

International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459, Volume 1, Issue 2, December 2011)

19

III.

R

ESULT

A

ND

D

ISCUSSION

According to the design dimensions given above, the tri-wide- band antenna was designed and simulated on IE3D.The simulated reflection coefficient of the antenna is shown in Fig. 5. It is seen from the results that two wide and one narrow operating bands centered at about 1.9 GHz, 3 GHz a n d 5 GHz and are excited with good impedance matching. The -10dB impedance bandwidths for the lower and upper bands reach 200MHz (1.84–2.04 GHz), 1100 MHz (2.40–3.50 GHz) and 2030 MHz ( 4.36-6.39 GHz) respectively, which are able to cover the 2.4/5.2/5.8 GHz WLAN bands and 2.5/3.5/5.5 GHz WiMAX bands.

To demonstrate the effect of the triangular monopole and the U-shaped monopole on generating the antenna’s lower and upper bands, the simulated reflection coefficient ( in Figure 6.), Current distribution (in Figure 5), Directivity (in Figure 9), Gain (in Figure7) of the assembled antenna are presented. It is seen that first mode at about 1.9 GHz, second mode at about3GHz and a second mode at about 5.2 GHz are obtained with return loss of -14.5, -33.95 and -38.68 respectively with a peak gain of 8.5dBi and peak directivity of 9.5dBi .

Figure.5.Current Distribution of Proposed antenna

Figure.6. Simulated reflection coefficient (S11 in dB)

characteristics of proposed planar antenna

Figure.7. Gain characteristic of Proposed antenna

(4)

International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459, Volume 1, Issue 2, December 2011)

20 Figure:9. Directivity characteristic of Proposed antenna

Figure10 : Axial ratio of proposed antenna

(a)

(b)

(c)

Figure.11 .Azimuth radiation pattern of proposed antenna at different band Frequencies

IV. CONCLUSION &FUTURE WORK

(5)

International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459, Volume 1, Issue 2, December 2011)

21 In future , the gain and bandwidth of antenna can be enhanced by using parasitic patch, L probe feed or by introducing an air gap between ground plane and dielectric[11] . By using some different fractal geometries this antenna can also be used for lower band of frequencies with size miniaturization [10].

References

[1] H. D. Chen, J. S. Chen, and Y. T. Cheng, “Modified inverted-L monopole antenna for 2.4/5 GHz dual-band operations,” Electron. Lett., vol. 39, no. 22, Oct. 2003.

[2] S. B. Chen, Y. C. Jiao, W. Wang, and F. S. Zhang, “Modified T-shaped planar monopole antennas for multiband operation,” IEEE Trans. Mi- crow. Theory Tech., vol. 54, no. 8, pp. 3267–3270, 2006.

[3] X. C. Lin and C. C. Yu, “A dual-band CPW-fed inductive slot-monopole hybrid antenna,” IEEE Trans. Antennas Propag., vol. 56, no. 1, pp. 282–285, Jul. 2008.

[4] T. H. Kim and D. C. Park, “Compact dual-band antenna with double L-slits for WLAN operations,” IEEE Antennas Wireless Propag. Lett., vol. 4, pp. 249–252, 2005.

[5] Y. L. Kuo and K. L. Wong, “Printed double-T monopole antenna for 2.4/5.2 GHz dual band WLAN operations,” IEEE Trans. Antennas Propag., vol. 51, no. 9, pp. 2187– 2192, Sep. 2003.

[6] C. Y. Pan, T. S. Horng, W. S. Chen, and C. H. Huang, “Dual wideband printed monopole antenna for WLAN/WiMAX applications,” IEEE Antennas Wireless Propag. Lett., vol. 6, pp. 149–151, 2007.

[7] J. I. Kim and Y. Jee, “Design of ultrawideband coplanar waveguide-fed LI-shape planar monopole antennas,” IEEE Antennas Wireless Propag.Lett., vol. 6, pp. 383–387, 2007.

[8] Q. X. Chu and Y. Y. Yang, “A compact ultrawideband

antenna with 3.4/5.5 GHz dual band-notched

characteristics,” IEEE Trans. Antennas Propag., vol. 56, no. 12, pp. 3637–3644, 2008.

[9] Qing-Xin Chu and Liang-Hua Ye, “Design of Compact Dual band compact dual wideband antenna with assembled monopoles,” IEEE Trans. Antennas Propag., vol. 58, no. 12, Dec 2010.

[10] John P. Gianvittorrio and Yahya Rahmat-samii, “Fractal Antennas: A Novel Antenna Miniaturization Technique and Applications”, IEEE Antenna and Propagation Magazine, pp. 20 – 36, 44 (1), 2002.

Figure

Figure.2. Geometry of proposed antenna with finite ground Plane

References

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