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1 Tri-band Planar Monopole Antenna with Compact Radiator for WLAN / Wi-MAX Applications 1 S. Ramkumar, 2 M.V.S. Prasad, 3 K. Prasuna 1 Assistant Professor, Dept. of ECE, Lingayas Institute of Management and Tech., A.P., India 2 Professor, Department of ECE, R.V.R & J C college of Engineering, A.P., India 3 Assistant Professor, Department of ECE, Vijaya Institute of Technology for Women, A.P., India Abstract: In recent years, great interest was focused on microstrip antennas for their small volumes, low profiles, good integration, low costs and good performance. With the continuous growth of wireless communication service and the constant miniaturization of communication equipment, there are higher and higher demands for the volume of antennas, integration and working band. This paper presents a compact CPW fed monopole antenna with triple band for wireless communications system application which are suitable for the 2.4-GHz, 3.5-GHz and the 5-GHz triple-band operations. These systems may include various combinations of Bluetooth, WiMAX (Worldwide Interoperability for Microwave Access) and wireless local-area network (WLAN). Keywords: Triple Band, Compact radiator, WLAN, Wi-MAX Introduction: The rapid progress in wireless communications requires the development of lightweight, low profile, flush-mounted and single-feed antennas. Also, it is highly desirable to integrate several RF modules for different frequencies into one piece of equipment. Hence, multi-band antennas that can be used simultaneously in different standards have been in the focus points of many research projects [1-3]. Among these standards, the following frequency bands can be mentioned: First frequency 2.4 GHz Second frequency 3.5 GHz Third frequency 5.2 GHz Microstrip antennas are very attractive because of their low profile, low weight, conformal to the surface of objects and easy production. A large number of microstrip patches to be used in wireless applications have been developed [4 6]. Various shapes such as square, rectangle, ring, disc, triangle, elliptic, etc. have been introduced [7 10]. In comparison to patch elements, the antennas with slot configurations demonstrate enhanced characteristics, including wider bandwidth, less conductor loss and better isolation. Particularly, the multi-slot structure is a versatile approach for multi-band and broadband design. Also, feeding these structures could be simpler by using suitable points to slot techniques for different slots. WLAN has made rapid progress and there are several IEEE standards already, namely a, b, g and n. Which used

2 the bands of 2.4 (GHz) band 2.4 to and 5.2 (GHz) band 5.15 to 5.35 (GHz) with the development of WLAN. Simulated results are performed by using commercial software HFSS. Also sweep displacement ranging vertically & horizontally is performed to examine the effect of the slot displacement on the return loss and find out the optimum place to get the best performance on the return loss. Antenna design is shown in Fig 1, which indicates different iterations of the design at different levels. Fig 1(a) Monopole Antenna, Fig 1(b)&(c) L-Shaped slot loaded monopole antennas, Fig 1(d) Combined L- Shaped slotted monopole Fig 2 Dimensional Characteristics of the proposed antenna

3 L=21, W=29, L0=5, W0 =15, L1=9, W1=0.8, L2=13.4, W2=0.3, L3=17,W3=0.9, Lg=12, Wg=8.25, Wf=3.5, G=0.5 Results and Discussion: Fig 3 shows the return loss curve for all the iterative designs. Triple band with considerable impedance bandwidth can be observed from the results. A minimum bandwidth of 1.65 GHz is obtained at resonant Frequencies GHz, GHz and GHz respectively with minimum return loss of dB, dB and dB respectively. An impedance bandwidth of 36.4%, at first resonant frequency, 13.5% at second resonant frequency and 22% at third resonant frequency. Final optimization is conducted for better radiation performance at the desired frequencies. For this purpose, some areas are subtracted from the top and bottom parts of the main-center patch. The shape of the subtracted area is in Figure 2 and the effects on the parameters are presented in Fig Return Loss Comparison Multiband MPA Return Loss (db) Curve Info Antenna-1 Antenna-2 Antenna-3 Antenna-4 Antenna-5 Setup1 : Sweep Frequency [GHz] Fig 3 Simulated Return loss Vs Frequency for all the iterations Return Loss Multiband MPA Curve Info db(st(1,1)) Setup1 : Sw eep m S Name X Y m m m m2 m Frequency [GHz] Fig 4 Return loss for optimized model

4 VSWR m1 Name X Y m m m m2 VSWR Multiband MPA Freq [GHz] Fig 5 VSWR Vs Frequency m3 Curve Info VSWRt(Patch_T1) Setup1 : Sweep1 VSWR less than 2 at the operating bands can be observed from Fig 5. Fig 6 shows the input impedance of the antenna in smith chart. The corresponding impedance at the resonant frequencies are presented in this result. Fig 6 Input impedance smith chart

5 Fig 7 Radiation pattern of the antenna at three resonant frequencies in E and H-plane Fig 7 shows the radiation pattern of the antenna with HPBW at GHz is deg, GHz is deg, and at GHz is in E-Plane. A peak realized gain of 2.34 db is attained at 5.02 GHz from Fig 8. Fig 8 Three dimensional radiation view Fig 9 Surface Current Distributions at GHz, GHz, GHz The cross polarization is low compared to co-polarization from radiation pattern curves. The simulated current distribution is shown in Fig 9, which indicates the intensity of the current at feed and radiating element is more at lower bands than higher band.

6 Conclusion: A new inverted l-slotted shaped microstrip CPW feed patch antenna has been designed and presented in this work. The feeding technique, the adjusted slotted patch shape and the dimensions of the antenna is made it possible, to modify the acceptable reflection coefficient and characteristics of the radiation pattern in the expected frequency. The different parametric study, gain and radiation pattern of the proposed antenna is also analyzed and discussed. For omnidirectional radiation pattern and high gain, the proposed triple band antenna can be a competitive solution for the current needs to be adopted with multi technology wireless devices in communication applications compare to other available dual band multi frequency antennas. Acknowledgements: Author S.Ramkumar would like to express his gratitude towards M.V.S. Prasad for his guidance and K.Prasuna for her support during the work. References: [1] Costantine,J.,K. Y. Kabalan,A. El Hajj,and M. Rammal, New multi-band microstrip antenna design for wireless communications, IEEE Antennas and Propagation Magazine,Vol. 48,No. 6, ,December [2] H. Sabri and Z. Atlasbaf "Two Novel Compact Triple-Band Microstrip Annular-Ring Slot Antenna For PCS AND WLAN Applications" Progress In Electromagnetic Research Letters, Vol. 5, 87 98, 2008 [3] B.T.P.Madhav, VGKM Pisipati, K.V.L.Bhavani, Dara.Harish, B.Rajasekhar Reddy, P.Ravikishore, TRIPLE BAND T-STRIP SLOTTED MICROSTRIP PATCH ANTENNA FOR MOBILE COMMUNCATION, [IJESAT] INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE & ADVANCED TECHNOLOGY, ISSN: , Volume - 2, Issue - 1, , Cited by 2. [4] B.T.P.Madhav, N.Suresh, VGKM Pisipati, Srikanth Sattenapalli, N.Jyothirmai, H-Shaped Triple Band MSPA for Cellular Phone Applications, International Journal of Emerging trends in Engineering and Development, ISSN Issue 2, Vol.1, January [5] G.Asa Jyothi, P.Siddaiah, B. Prabhakar Rao, B.T.P.Madhav, Triple Band Triangular and Exponential Serrated MSP Antennas for S and C Band Applications, International Journal of Engineering Research and Development, e- ISSN: X, p-issn: X, Volume 5, Issue 4 (December 2012), PP [6] R. K. Gupta "Printed TRI-BAND Monopole Antenna Structures For Wireless Applications" Issue 2, Vol I, Apr 2010 [7] M. A. S. Alkanhal, "Composite Compact Triple-Band Microstrip Antennas, "Progress In Electromagnetics Research, PIER 93, , 2009 [8] Jawad K. Ali "A New Compact Size Microstrip Patch Antenna with Irregular Slots for Handheld GPS Application" Eng.& Technology,Vol.26,No.10, 2008 [9] D. N. Elsheakh, H. A. Elsadek, and E. A. Abdullah "Reconfigurable Single and MultiBand Inset Feed Microstrip Patch Antenna For Wireless Communication Devices" Progress In Electromagnetics Research C, Vol. 12, 191{201, [10]Raj Kumar, George Mathai and J.P. Shinde "Design of Compact Multiband EBG and Effect on Antenna Performance " International Journal of Recent Trends in Engineering, Vol 2, No. 5, November 2009.