International Journal of Emerging trends in Engineering and DevelopmentIssue 2, Vol.4 (May 2012) ISSN 2249-6149Page 178Performance Investigation of TriangularToothed Serrated Microstrip Patch Antennas1B.T.P.Madhav, 1VGKM Pisipati, 2Anjaneyulu Badugu, 2Y. Sudha Vani1LCRC-R&D, Department Of ECE, K L University, AP, India2Asst.Professor, ECE Department, Chebrolu Engineering College, Chebrolu, Guntur (D.T)____________________________________________________________________________________________________Abstract:The performance characteristics of microstrip patch antennas depend on various factors like substrate materialselection, dimensions of the patch, substrate, feeding mechanism etc. This paper presents the performanceinvestigation on three types of triangular toothed serrated microstrip patch antennas. All these antennas arehaving different patch dimensions, but having triangular tooth on its edges. The output parameters of all theseantennas are simulated using HFSS and the comparative analysis is presented in this paper. Among threemodels, two models are resonating at dual frequency and one model is resonating at triple frequency.Keywords: Triangular Tooth, Serrations, MSPA____________________________________________________________________________________________________Corresponding Author: B.T.P.MadhavI. INTRODUCTION:Microstrip antenna consists of a radiating patch and a ground plane on either side of a dielectric substance. Thepatch is very thin and is usually made of conducting materials such as gold and copper. There are wide numberof substrates that can be used for the design of microstrip patch antenna. Thick substrates are desirable forantenna performance. This type of substrates has dielectric constant in the lower end of the range. This is due tolarger bandwidth, better efficiency, and loosely bound fields for radiation into space but results in large elementsize. With the increase in frequency, lower permittivity and thicker substrate, the radiation increases [1-3].A good compromise has to be reached between circuit design and good antenna performance as microstripantennas are usually integrated with other microwave circuitry. Photo etching of feed lines and radiatingelement is generally done on the dielectric substrate. The radiating patch may be of any configuration such assquare, dipole or thin strip, circular, rectangular, elliptical and triangular [4-6]. A microstrip antenna is made fora broad range of resonant frequencies, impedance, polarization patterns and is very flexible. Microstrip antennashave different feeding methods: Micro-strip line, coaxial-line feed and proximity coupled feed.Microstrip antennas are widely used on mobile phones, laptops, microcomputers etc. These are also applicablewhere narrow bandwidth is preferred such as in government security systems and mobile due to its operationalfeatures like low power, low efficiency, poor polarization purity, poor scan performance, high quality factor,narrow bandwidth. Circularly polarized microstrip antenna has wide applications in military. These aremechanically robust. These antennas have few disadvantages such as low impedance bandwidth, low gain andextra radiation at its feed and junctions. Size of microstrip antenna is sometimes an advantage or disadvantagedepending on the application [7-10].The present paper deals with different serrated models of triangular toothed antennas with different dimensionsand their performance comparison. For two models the serrated triangular tooth are at the external edges and forone model the triangular tooth is inner side of the patch edge. External edged triangular patch antennas areresonating at dual frequency and the inner edged triangular toothed patch antenna resonating at triple band.Three models of the antennas are as shown in the figure (1).
International Journal of Emerging trends in Engineering and DevelopmentIssue 2, Vol.4 (May 2012) ISSN 2249-6149Page 179Figure (1) Triangular Serrated MSPA ModelsII. RESULTS AND ANALYSIS:Figure (2) shows the return loss Vs frequency curve for the three disigned models. The first and second antennasare resonating at dual frequency and the third antenna is resonating at triple band and all the resonantfrequencies are giving excellent reflection coefficient parameter values i.e., < -10dB in the entire range. The firstmodel of 36 element triangular external toothed antenna is resonating at 4.08 and 6.26 GHz with return loss of -21.53dB and -23.76dB respectively. The second model of 18 element triangular external toothed antenna isresonating at 4.3 and 6.8 GHz with return loss of -19.01dB and -18.8dB respectively. The Third model of 36element triangular internal toothed antenna is resonating at 3.7, 5.9 and 7.5 GHz with return loss of -19.59dB, -24.76 and -19.76dB respectively.
International Journal of Emerging trends in Engineering and DevelopmentIssue 2, Vol.4 (May 2012) ISSN 2249-6149Page 1802.00 3.00 4.00 5.00 6.00 7.00 8.00Freq [GHz]-25.00-20.00-15.00-10.00-5.000.00dB(St(1,1))Ansoft Corporation Patch_Antenna_ADKv1Return Lossm 1m 2Curve InfodB(St(1,1))Setup1 : Sw eep1Name X Ym1 4.0829 -21.5376m2 6.2688 -23.7656Name Delta(X) Delta(Y) Slope(Y) InvSlope(Y)d(m1,m2) 2.1859 -2.2280 -1.0192 -0.98112.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00Freq [GHz]-20.00-15.00-10.00-5.000.00dB(St(1,1))Ansoft Corporation Patch_Antenna_ADKv1Return Lossm 1 m 2Curve InfodB(St(1,1))Setup1 : Sw eep1Name X Ym1 4.3010 -19.0166m2 6.8518 -18.8918Name Delta(X) Delta(Y) Slope(Y) InvSlope(Y)d(m1,m2) 2.5508 0.1248 0.0489 20.43812.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00Freq [GHz]-25.00-20.00-15.00-10.00-5.000.00dB(St(1,1))Ansoft Corporation Patch_Antenna_ADKv1Return Lossm 1m 2m 3Curve InfodB(St(1,1))Setup1 : Sw eep1Name X Ym1 3.7854 -19.5958m2 5.9563 -24.7679m3 7.5573 -19.7625Figure (2) Return Loss Vs Frequency5.002.001.000.500.205.00-5.002.00-2.001.00-1.000.50-0.500.20-0.200.00-0.000102030405060708090100110120130140150160170180-170-160-150-140-130-120-110-100 -90 -80-70-60-50-40-30-20-10Ansoft Corporation Patch_Antenna_ADKv1Input ImpedanceCurve Info bandw idth(1, 0)St(1,1))Setup1 : Sw eep13.74665.002.001.000.500.205.00-5.002.00-2.001.00-1.000.50-0.500.20-0.200.00-0.000102030405060708090100110120130140150160170180-170-160-150-140-130-120-110-100 -90 -80-70-60-50-40-30-20-10Ansoft Corporation Patch_Antenna_ADKv1Input ImpedanceCurve Info bandw idth(1, 0)St(1,1))Setup1 : Sw eep13.95055.002.001.000.500.205.00-5.002.00-2.001.00-1.000.50-0.500.20-0.200.00-0.000102030405060708090100110120130140150160170180-170-160-150-140-130-120-110-100 -90 -80-70-60-50-40-30-20-10Ansoft Corporation Patch_Antenna_ADKv1Input ImpedanceCurve Info bandw idth(1, 0)St(1,1))Setup1 : Sw eep13.5711Figure (3) Input Impedance Smith ChartFigure (3) shows the input impedance smith chart for all the three models of serrated triangular toothedantennas. The input impedance at the feed of the antenna isZ = R+jX =VIEavtI
International Journal of Emerging trends in Engineering and DevelopmentIssue 2, Vol.4 (May 2012) ISSN 2249-6149Page 181where Eav is the average value of the electric field at the feed point and I is the total current.The input impedance is complex and involves a resistive and reactive part. The resistive and reactivecomponents vary as a function of frequency and are symmetric around the resonant frequency.For a probe fed circular patch, the input impedance with near resonance can be represented as afunction of frequency and feed location as,Zin(f, P) = Rin(f, P)+jXin(f, P)The input resistance at resonance varies with radial distance P from the centre of the patch as,Rin(f = fr, nm, P) = Rr(P) =RedgeJn2(kPoaaeff)Jn2(ka)The input impedance of a rectangular patch and feed location expressed as the functions of frequencyand feed location (xo, yo) as,Zin(f, xo) = Rin(f, xo)+jXin(f, xo)As per the input impedance bandwidth is concerned 0.92, 0.93 and 0.94% enhancement is obtained formodels from one to three.Figure (4) Radiation Pattern in Phi and Theta DirectionFor each mode, there are two orthogonal planes in the far field region. One designated as E-plane and the otherdesignated as H-plane. The far zone electric field lies in the E-plane and the far zone magnetic field lies in theH-plane. The patterns in these planes are referred to as the E and H plane patterns respectively. Figure (40shows the radiation pattern in three dimensional view for all the three models in phi and theta direction.
International Journal of Emerging trends in Engineering and DevelopmentIssue 2, Vol.4 (May 2012) ISSN 2249-6149Page 182For the TM01 mode, the contributions to the far fields are from the magnetic surface currentdensities on the side walls containing the radiating edges. The directions of the magnetic currents that the E-plane is the y-z plane (Φ=90º) and the H-plane is the x-z plane (Φ=0º). For the TM10 mode, the E-plane is the x-z plane (Φ=0º) and the H-plane is the y-z plane (Φ=90º)E (r,,) 2whE00cos(1 TTM())cos kxL2sinc kyw2tanc(kz1h)E (r,,) 2whE00(cossin)(1 TTE())cos kxL2sinc kyw2tanc(kz1h)Figure (5) Surface Current DistributionFigure (5) shows the surface current distribution for the three models. Figure (6) shows the axial ratio for allthree models. The axial ratio of an elliptically polarized wave is defined as, axial ratio=B/A. Pure circularpolarization occurs if the axial ratio is equal to unity. The axial ratio is therefore a parameter which measures thepurity of the circularly polarized wave. Perfect circular polarization may be produced by an antenna only at aparticular frequency fo. The axial ratio will be larger than unity when the frequency deviates from fo.The range of frequencies for which axial ratio is smaller than a specified value is defined asthe axial ratio band width (ARBW). Usually this specified value is 3db. Some applications require a smallervalue. The axial ratio bandwidth should be within the impedance bandwidth or return loss band width (RLBW)if the antenna is to be useful.
International Journal of Emerging trends in Engineering and DevelopmentIssue 2, Vol.4 (May 2012) ISSN 2249-6149Page 183Figure (6) Axial RatioIII. CONCLUSION:All the three models are showing excellent and moderate results for the applicability of these antennas in dualand triple band applications. First model is resonating at dual band with gain of 7.0127dB, peak directivity of5.0722, radiated power of 0.00085238 and radiation efficiency of 0.991. The second model is also resonating atdual mode with gain of 6.5074dB, peak directivity of 4.5471, radiated power of 0.00073617 and radiationefficiency of 0.985. The third model is resonating at triple band with gain of 7.72dB, peak directivity of 6.01,radiated power 0.0012922 and radiation efficiency of 0.984. Overall the third model is giving better gain andradiated power compared to other models. The second model is showing lesser performance characteristicscompared to other models but radiation efficiency is better than third model. The performance characteristics bychanging the dimensions of the patch with respect to serrations are analyzed and presented in this work.ACKNOWLEDGMENTSThe authors B.T.P.Madhav, Prof. VGKM Pisipati and T.V.Ramakrishna express their thanks to the managementof K L University and Department of Electronics and Communication Engineering for their support. Further,VGKM Pisipati acknowledges the financial support of Department of Science and Technology through the grantNo.SR/S2/CMP-0071/2008.REFERENCES K. L. Wong and J. Y. Sze, “Dual-frequency slotted rectangular microstrip antenna,” Electron. Lett. 34,1368–1370, July 9, 1998. J. H. Lu, “Single-feed dual-frequency rectangular microstrip antenna with pair of step-slots,” Electron. Lett.35, 354–355, March 4, 1999. K. S. Kim, T. Kim, and J. Choi, “Dual-frequency aperture-coupled square patch antenna with doublenotches,” Microwave Opt. Technol. Lett. 24, 370–374, March 20, 2000.
International Journal of Emerging trends in Engineering and DevelopmentIssue 2, Vol.4 (May 2012) ISSN 2249-6149Page 184 C. C. Huang, Dual-frequency microstrip arrays with a dual-frequency feed network, M.S. thesis, Departmentof Electrical Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan, 2000. S. T. Fang and K. L. Wong, “A dual-frequency equilateral-triangular microstrip antenna with a pair ofnarrow slots,” Microwave Opt. Technol. Lett. 23, 82–84, Oct. 20, 1999. K. P. Yang, Studies of compact dual-frequency microstrip antennas, Ph.D. dissertation, Department ofElectrical Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan, 1999. J. H. Lu and K. L. Wong, “Compact dual-frequency circular microstrip antenna with an offset circular slot,”Microwave Opt. Technol. Lett. 22, 254–256, Aug. 20, 1999. W. P. Dou and Y. W. M. Chia, “Novel meandered planar inverted-F antenna for triple-frequency operation,”Microwave Opt. Technol. Lett. 27, 58–60, Oct. 5, 2000. G. S. Row, S. H. Yeh, and K. L. Wong, “Compact dual-polarized microstrip antennas,” Microwave Opt.Technol. Lett. 27, 284–287, Nov. 20, 2000. T. W. Chiou and K. L. Wong, “Designs of compact microstrip antennas with a slotted ground plane,” in2001 IEEE Antennas Propagat. Soc. Int. Symp. Dig., pp. 732–735.Authors Biography:B.T.P.Madhav was born in India, A.P, in 1981. He received the B.Sc, M.Sc, MBA, M.Tech degrees from NagarjunaUniversity, A.P, India in 2001, 2003, 2007, and 2009 respectively. From 2003-2007 he worked as lecturer and from 2007 totill date he is working as Associate Professor in Electronics Engineering. He has published more than 80 papers inInternational and National journals. His research interests include antennas, liquid crystals applications and wirelesscommunications.Prof. VGKM Pisipati was born in India, A.P, in 1944. He received his B.Sc, M.Sc and PhD degrees from AndhraUniversity. Since 1975 he has been with physics department at Acharya Nagarjuna University as Professor, Head, R&DDirector. He guided 22 PhDs and more than 20 M.Phils. His area of research includes liquid crystals, nanotechnology andliquid crystals applications. He visited so many countries and he is having more than 320 International research publications.He served different positions as academician and successfully completed different projects sponsored by differentgovernment and non-government bodies. He is having 5 patents to his credit.Anjaneyulu Badugu was born in India.in 1987. He did his B.Tech under JNTU and M.Tech from K LUniversity. Presently he is working as Asst.Professor in ECE Department of Chebrolu Engineering College. His researchInterests includes Antennas and Digital Communication.