International Journal of Electronics and Computer Science Engineering 1561

Transcription

1 International Journal of Electronics and Computer Science Engineering 161 Available Online at ISSN A compact printed Antenna for WiMAX Application Barun Mazumdar Department of Electronics and Communication Engineering Aryabhatta Institute for Engineering and Management, Durgapur, West Bengal, India barun_bm@rediffmail.com Abstract- A single feed compact microstrip antenna is proposed in this paper. Two L slits are introduced at right side of the patch. For the proposed antenna resonant frequencies are obtained at 3.48 GHz, 4.34 GHz and.6 GHz with bandwidth of 19 MHz, return loss 2.2 db, 42.6 MHz, return loss -3. db and bandwidth of 39.2 MHz, return loss -2.2 db respectively. The size of the antenna has been reduced by 66 % when compared to a conventional microstrip patch. Keywords Conventional, patch, slit I. INTRODUCTION In wireless communication [1-3], there are several types of microstrip antennas the most common of which is the microstrip patch antennas [4]. There are varieties of patch structures available but the rectangular, circular and triangular shapes are most frequently used. WiMax [-7] stands for Worldwide Interoperability for Microwave access and it has been established by the IEEE working group. It has three operating bands, the low band ( GHz), the middle band ( GHz) and the upper band (.2.8 GHz). The work to be presented in this paper is a compact microstrip antenna design obtained by cutting L slit on the patch. The proposed dual band antenna (substrate with ε r =4.4) simulated for the WiMax frequency ranges of GHz &.2.8 GHz. It has a gain of 2 dbi at 3.48 GHz,.43 dbi at 4.34 GHz and 3 dbi at.6 GHz and presents a size reduction of about 66% when compared to a conventional microstrip patch. The simulation has been carried out by IE3D software which uses the MOM method. II. ANTENNA DESIGN The configuration of the proposed antenna is shown in Figure 1. The antenna is a 1 mm x 12 mm rectangular patch. The dielectric material selected for this design is an FR4 epoxy with dielectric constant (ε r ) =4.4 and substrate height (h) =1.87 mm. Figure 1. Antenna Configuration The optimal parameter values of the antenna are listed in Table: Parameters w 1 w 2 w 3 l 1 l 2 m n o p q r s t Values(mm) ISSN /V1N3616

2 IJECSE,Volume1,Number 3 B Mazumdar et al. 162 III. EXPERIMENT AND RESULT Simulated (using IE3D [1]) results of return loss of the Conventional & proposed antenna are shown in Figure 2 & 3. In Conventional antenna only one frequency is obtained below -1 db which is.6 GHz & return loss is found about with.133 GHz bandwidth. For the proposed antenna resonant frequencies are 3.48 GHz, 4.34GHz,.6GHz and their corresponding return losses are -2.2 db, -3. db & -2.2 db respectively. Simulated 1 db bandwidths are 19 MHz, 42.6 MHz & 39.2 MHz respectively Figure 2. Return loss of the Conventional antenna. Simulated Radiation pattern Return loss of the proposed antenna. The simulated E H plane radiation patterns for proposed antenna are shown in Figure 3. Figure 3. E plane Radiation Pattern of the antenna for 3.48 GHz H plane Radiation Pattern of the antenna for 3.48 GHz ISSN /V1N3616

3 A compact printed Antenna for WiMAX Application 163 Figure 4. E plane Radiation Pattern of the antenna for 4.34 GHz H plane Radiation Pattern of the antenna for 4.34 GHz Figure. E plane Radiation Pattern of the antenna for.6 GHz H plane Radiation Pattern of the antenna for.6 GHz Fig 6 shows the total field gain versus frequency plot for the antenna 2.It is observed that antenna gain is about 2 dbi for 3.48 GHz band,.43 dbi for 4.34 GHz, and.6ghz band antenna gain lies 3 dbi. ISSN /V1N3616

4 IJECSE,Volume1,Number 3 B Mazumdar et al Gain in dbi Frequecy in GHz Figure 6. Gain versus frequency plot for the proposed antenna. Efficiency of the antenna 2 (radiating efficiency and antenna efficiency) with the variation of frequency is shown in figure 7.It is found that for the lower band of operation efficiency of the antenna is about 38 %, for middle band 8 % & for higher it is 43 %. 1 Antenna efficiency Radiating efficiency 8 Efficiency in Percentage Frequency in Ghz Figure 7. Antenna efficiency versus frequency plot for the proposed antenna. IV. EXPERIMENTAL RESULTS Comparisons between the measured return losses with the simulated ones are shown in Fig.8. All the measurements are carried out using Vector Network Analyzer (VNA) Agilent N 23A.The agreement between the simulated and measured data is reasonably good. The discrepancy between the measured and simulated results is due to the effect of improper soldering of SMA connector or fabrication tolerance. ISSN /V1N3616

5 16 A compact printed Antenna for WiMAX Application Simulated result Measuredresult Simulated result Measuredresult Figure 8. Comparison between measured and simulated return losses for conventional antenna Comparison between measured and simulated return losses for proposed antenna V.CONCLUSION A single feed single layer L slit microstrip antenna has been proposed in this paper. It is shown that the proposed antenna can operate in three frequency bands. L slit reduced the size of the antenna by 66 % increase the bandwidth upto 42.6 MHz with a return loss of -3. db & absolute gain about.43 dbi. Efficiency of antenna has been achieved about 38 % for the lower band, 8 % for the middle band and 43 % for the higher band of operation. Alteration of the location of the L slit can more reduce the lower resonant frequency but divide the lower band into two different bands with lower value of bandwidth. An optimization between size reduction and bandwidth enhancement is maintained in this work. VI. REFERENCE [1] F. Yang, X. -X. Zhang, X. Ye, and Y. Rahmat-Samii, Wide-Band Eshaped Patch Antennas for Wireless Communications, IEEE Trans. Antennas Propagat., vol. 49, no. 7, pp , July. 21. [2] R. L. Li, B. Pan, T. Wu, J. Laskar, and M. M.Tentzeris A Triple-Band Low-Profile Planar Antenna for Wireless Applications" December1, 28, IEEE Explore. [3] F. Yang, X. -X. Zhang, X. Ye, and Y. Rahmat-Samii, Wide-Band Eshaped Patch Antennas for Wireless Communications, IEEE Trans. Antennas Propagat., vol. 49, no. 7, pp , July. 21. [4] S. Bhunia, M.-K. Pain, S. Biswas, D. Sarkar, P. P. Sarkar, and B. Gupta, Investigations on Microstrip Patch Antennas with Different slots and Feeding Points, Microwave and Optical Technology Letters, VOL, NO. 11, November 28 pp [] P. Pigin, Emerging mobile WiMax antenna technologies, IET Communication Engineer, October/ November 26. [6] C. T. Lee and K.L Wong, Uniplanar printed coupled-fed PIFA with a band-notching slit for WLAN/WiMAX operation in the laptop computer, IEEE APS, vol. 7, pp , April 29. [7] U.Chakraborty, B.Mazumdar, S. K. Chowdhury, and A. K. Bhattacharjee, A Compact L-slot Microstrip Antenna for Quad band Applications in Wireless Communication, Global Journal Of Researches in Engineering (F) Volume XII Issue II Version I Feb,212. [8] C.A.Balanis, Advanced Engineering Electromagnetics, John Wiley & Sons., New York, [9] I.J. Bahl and P. Bhartia, Microstrip Antennas, Artech House, Dedham, MA, 198. [1] Zeland Software Inc. IE3D: MoM-Based EM Simulator. Web: ISSN /V1N3616