DUAL BAND COMPACT MICROSTRIP PATCH ANTENNA WITH DEFECTED GROUND STRUCTURE

Transcription

1 International Journal of Electronics and Communication Engineering & Technology (IJECET) Volume 6, Issue 9, Sep 2015, pp , Article ID: IJECET_06_09_009 Available online at ISSN Print: and ISSN Online: 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 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 75 editor@iaeme.com

2 Rashmi A. Pandhare and Prasanna L. Zade 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 mm with dielectric constant of 2.2 and the loss tangent 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 76 editor@iaeme.com

3 Dual Band Compact Microstrip Patch Antenna with Defected Ground Structure 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 [S 11 ] db of the antenna without any DGS in ground plane resonates at 5.2 GHz at 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 77 editor@iaeme.com

4 Rashmi A. Pandhare and Prasanna L. Zade 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 S 11 versus frequency indicating resonant at 3.5GHz and 5.2GHz simultaneously Figure 7 Radiation pattern with DGS 78 editor@iaeme.com

5 Dual Band Compact Microstrip Patch Antenna with Defected Ground Structure 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 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 editor@iaeme.com

6 Rashmi A. Pandhare and Prasanna L. Zade 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 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. REFERANCES [1] Balanis, C.A., Antenna Theory: Analysis and Design, John Wiley & Sons, Inc, [2] Srijita Chakraboty, Sayan K. Moitra, Soham Tewary, Design and Analysis of Dual Band, DGS Integrated Compact Microstrip Antenna, Advances in Optical science and Engineering, 166, pp , 2015 [3] L. H. Weng, Y. C. Guo, X. W. Shi, and X. Q. Chen. An Overview on Defected Ground Structure, Progress In Electromagnetics Research B, (7), , 2008 [4] Lo, T.K. and Y. Hwang, Microstrip antennas of high permittivity for personal communication, 1997 Asia Pacific Microwave Conference, , [5] Tirado-Mendez, J. A., M. A. Peyrot-Solis, H. Jardon-Aguilar, E. A. Andrade- Gonzalez, and M. Reyes-Ayala, Applications of novel defected microstrip structure (DMS) in planar passive circuits, Proceedings of the 10th WSEAS International Conference on CIRCUITS, , Vouliagmeni, Athens, Greece, Jul , editor@iaeme.com

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