Circularly Polarized Wideband Archimedean Spiral Antenna

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1 Volume 1, No. 4, June 2012 ISSN The International Journal of Computer Science & Applications (TIJCSA) RESEARCH PAPER Available Online at Circularly Polarized Wideband Archimedean Spiral Antenna 1* B.T.P.Madhav, 2 Ch. Raja, 3 K. Praveen Kumar, 4 Rakesh Narsingu, 5 Koti Reddy.G 1 Associate Professor, Department of ECE, K L University, Guntur DT, AP, India 2 Associate Professor, Department of ECE, MGIT, Hyderabad 3 Associate Professor, Department of ECE, Vani School of Engineering, Cheviture 4 Associate Professor, Department of ECE, KLR College of Engineering, Polancha 5 Assistant Professor, Department of ECE, KLR College of Engineering, Polancha Abstract: Archimedean antenna is one of the frequency independent antenna, used for wide and multiband applications. The Archimedean spiral is typically backed by a lossy cavity to achieve frequency bandwidths of 9:1 or greater. Here the spiral antenna is self complimentary due to metal and air regions are equal. The current paper deals with the simulation of Archimedean antenna operating between the frequency range of 4 to 10 GHz. The output parameters of the antenna and the analysis are presented in this paper with the help of commercial Ansoft HFSS software. Keywords: Circular Polarization, Archimedean antenna, Wideband, Multiband. 1. INTRODUCTION: The Archimedean spiral antenna is a very good candidate for UWB application but it has a major drawback because it is a dispersive system, which means that the delay within the antenna is frequency dependent. As a result, in any application where the shape of the pulse is important as, for instance in radar systems, a calibration procedure to remove the delays within the antenna system is needed [1-4]. For a self-complementary Archimedean spiral antenna in free space the input impedance should be Zin = η 0 /2 = ohms ---- (1) Each arm of an Archimedean spiral is linearly proportional to the angle ϕ and is described by the following relationships r = r 0 ϕ+r 1 and r = r 0 (ϕ - π) + r (2) 2012, - TIJCSA All Rights Reserved 1

2 Where r 1 is the inner radius of the spiral. The proportionality constant is determined from the width of each arm, w, and the spacing between each turn, s, which for a self complementary spiral is given by r 0 = (s + w)/π = 2w/π (3) Fig 1 Geometry of Archimedean spiral antenna The strip width of each arm S = ((r2 r1) / 2N) w = w (4) Thus the spacing or width may be written as S = w = (r2 r1) / 4N (5) Where r2 is the outer radius of the spiral and N is the number of turns. The above equations apply to a two-arm Archimedean spiral, but in some cases four-arm spirals may be desired [5-6]. In this case the arm width becomes W 4-arm = (r2 r1)/ 8N (6) The Archimedean spiral antenna radiates from a region where the circumference of the spiral equals one wavelength. This is called the active region of the spiral. Each arm of the spiral is fed 180 out of phase, so when the circumference of the spiral is one wavelength the currents at complementary or opposite points on each arm of the spiral add in phase in the far field [7-8]. The low frequency operating point of the spiral is determined theoretically by the outer radius and is given by f low = C/2πr (7) Where c is the speed of light. Similarly the high frequency operating point is based on the inner radius giving f high = C/2πr (8) Fig 2 Archimedean Antenna Design model 2012, - TIJCSA All Rights Reserved 2

3 Antenna design parameters: Archimedean antenna consists of two arms with inner radius of 0.48 cm and number of turns are Offset angle is 90, port extension 0.1 cm and port outer radius of cm. Results and Discussion: For the Archimedean spiral in free space a single feed wire connects each arm to a single voltage source at the center of the feed wire. Typically a wire radius of one quarter the desired strip width is used in simulations as an appropriate transformation from strip width to wire diameter Return Loss Archimedean_Antenna_ADKv1 ANSOFT Curve Inf o db(s(1,1)) Setup1 : Sw eep db(s(1,1)) Freq [GHz] Fig 3. Return loss Vs frequency Figure 3 shows the simulated return loss curve of the antenna. From the figure it is clear that the antenna is resonating between 4 GHz to 10 GHz with return loss less than -10dB. Figure 4 shows the gain in 3-dimensional curve and figure 5 shows the two dimensional gain curve. Fig 4. 3D gain Name X Y m ff_2d_gainrhcp m1 Archimedean_Antenna_ADKv1 Curve Inf o db(gainrhcp) Setup1 : LastAdaptive Phi='0deg' db(gainrhcp)_1 Setup1 : LastAdaptive Phi='90deg' ANSOFT Y Theta [deg] Fig 5. Two dimensional gain 2012, - TIJCSA All Rights Reserved 3

4 Fig 6. E-Field distribution Figure 6, 7 and 8 shows the E-field, H-field and surface current distribution of the antenna. Figure 9 shows the mesh generation plot of the current antenna. Fig 7. H-Field distribution Fig 8. Surface current distribution Fig 9. Mesh generation 2012, - TIJCSA All Rights Reserved 4

5 Figure 10 shows the VSWR Vs Frequency curve for the proposed antenna. The current model is showing acceptable range of VSWR with the value less than 2. From figure 10 VSWR of 1.25 is attained VSWR Archimedean_Antenna_ADKv1 ANSOFT Curve Inf o VSWR(p1) Setup1 : Sw eep VSWR(p1) Freq [GHz] Fig 10. VSWR Vs Frequency CONCLUSION: Spiral Archimedean antenna operating between the frequencies of 4 to 10 GHz is simulated and presented in the paper. Spiral performance can be improved by adding conductivity loss or resistive loading to the end of each arm to reduce reflections from the end of the spiral and improve low frequency impedance performance. Also, the spiral can be used over a ground plane for a wide frequency range by using a lossy ground plane or by using a conical ground plane to prevent pattern nulls. The antenna results of return loss less than -10dB for entire range and VSWR of 2:1 ratio and moderate gain are showing the applicability of the antenna in the wideband applications. ACKNOWLEDGMENTS: Authors like to express their thanks to the department of ECE and management of K L University, Vani School of Engineering, MGIT and K L R College of Engineering for their continuous support and encouragement during this work. Madhav also wants to express his gratitude towards Sri Koneru Satyanarayana Garu, Chancellor KLU for providing excellent R&D facilities in the KLU campus and promoting the research. REFERENCES: [1] I. Nicolaescu, P. van Genderen, and J. Zijderveld, Archimedean spiral antenna used for stepped frequency radar-footprint measurements, in Proceedinngs of the Antenna Measurement Techniques Association (AMTA 02), pp , Cleveland, Ohio, USA, November [2] Q. Liu, C.-L. Ruan, L. Peng, and W.-X. Wu, A NOVEL COMPACT ARCHIMEDEAN SPIRAL ANTENNA WITH GAP-LOADING, Progress In Electromagnetics Research Letters, Vol. 3, , [3] Wang, J. J. H., The spiral as a traveling wave structure for broadband antenna applications, Electromagnetics, 20 40, July August [4] Hosseini, S. A., Z. Atlasbaf, and K. Forooraghi, Two new loaded compact planar ultraband antennas using defected ground structures, Progress In Electromagnetics Research B, Vol. 2, , , - TIJCSA All Rights Reserved 5

6 1* B.T.P.Madhav, 2Ch. Raja, 3K. Praveen Kumar, 4Rakesh Narsingu, 5Koti Reddy. G, The [5] K. Nakayama and H. Nakano, Radiation characteristics of a conformal spiral antenna, Electron Commun Jpn Pt 1 83 (2000), [6] H. Nakano, M. Ikeda, K. Hitosugi, and J. Yamauchi, A spiral antenna sandwiched by dielectric layers, IEEE Trans Antennas Propagat 52 (2004), [7] M.N. Afsar, Y. Wang, and R. Cheung, Analysis and measurement of a broadband spiral antenna, IEEE Antennas Propagat Mag 46 (2004), [8] T. Cencich and J.A. Huffman, The analysis of wideband spiral antennas using modal decomposition, IEEE Antennas Propagat Mag 46 (2004), Author Biography: B.T.P.Madhav was born in India, A.P, in He received the B.Sc, M.Sc, MBA, M.Tech degrees from Nagarjuna University, A.P, India in 2001, 2003, 2007, and 2009 respectively. From he worked as lecturer and from 2007 to 2011 he worked as Assistant Professor and from 2011 to till date he is working as Associate Professor in Electronics and Communication Engineering. He has published more than 110 papers in International, National journals and Conferences. He is reviewer for three international journals and served as reviewer for three international conferences. His research interests include antennas, liquid crystals applications and wireless communications. He is a life member of ISTE, IACSIT, IRACST and UACEE. He is one of the editorial board member of IJETAE, TIJCSE, IJECR, and IJECSE. Technical board member of IJETTCS. Advisory board member of IJEIT and WARSE. Ch. Raja, Associate Professor, M.G.I.T, Hyderabad. Ch. Raja completed B.E (ECE) from Andhra University, Vizag in 1994 and M.Tech (DSCE) from JNTU,Hyderabad in 1999.Presently pursuing Ph.D. in JNTU, Hyderabad in the area of Radar Signal Processing(electronic warfare).presently working as an Associate professor in Mahatma Gandhi Institute of Technology,Hyderabad.He is having 16 years of teaching experience.he is a life member of ISTE and Fellow of IETE. He also visited the City University of Hong Kong, Hong Kong, as an Academic visitor for a period of two months in the year 2000.He has published several papers in international journals and conferences in the area of Electronic Warfare, Antennas and Image Processing. Praveen Kumar Kancherla was born in India, A.P, in He received the B.E(ECE) from Visveswaraiah Technological University, Belgaum M.Tech(Microwave Engineering) from Acharya Nagarjuna university, Gunture, A.P, India. He has 10 years of teaching experience in various engineering colleges in AP. and having more than 10 international, national journals/conference papers in his credit. His research interested areas includes Radar Signal Processing(electronic warfare), Antenna system designing, microwave engineering, Electro magnetics and RF system designing, liquid crystals applications and wireless communications. He is a 2012, - TIJCSA All Rights Reserved 6

7 Research scholar of JNTU Hyderabad in the field of Microwave Antennas. Mr. Praveen kumar.k is presently working as Head of the ECE department and DEAN Sri Vani School of Engineering affiliated to JNTUK Mr.Rakesh Narsingu working as an Associate Professor in the Depart of ECE at KLR College of Engineering & Technology, Paloncha And Holding the responsibility of Head Of Department of ECE. He Did his post graduation M.Tech form V.R.Siddhartha Engg College affiliated to A.N.U., and he obtained his B.Tech form Nova College of Engineering & Technology affiliated to JNTU,Hyderabad. Koti reddy gujjula working as Asst.prof in KLR college of Engg & Tech, paloncha. He did his M.Tech in embedded systems from Anurag Engg college, kodadain 2011, and B.Tech from Mother Theresa Institute of Science and Tech. Sattupalli in , - TIJCSA All Rights Reserved 7