International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN INTERNATIONAL JOURNAL OF ELECTRONICS AND 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 2, March – April (2013), © IAEME COMMUNICATION ENGINEERING & TECHNOLOGY (IJECET) ISSN 0976 – 6464(Print) ISSN 0976 – 6472(Online) Volume 4, Issue 2, March – April, 2013, pp. 15-22 IJECET © IAEME: www.iaeme.com/ijecet.asp Journal Impact Factor (2013): 5.8896 (Calculated by GISI) ©IAEME www.jifactor.com SELF-AFFINE RECTANGULAR FRACTAL ANTENNA WITH UC- EBG STRUCTURE Jagadeesha.S1, Vani R.M2, P.V Hunugund3 1 Department of Electronics & Communication, S.D.M Institute of Technology, Ujire- 574240, India 2 University of science & Instrumentation centre, Gulbarga University, Gulbarga- 5851006, India 3 Dept. of PG Studies and Research in Applied electronics,Gulbarga University, Gulbarga- 5851006,India ABSTRACT In this paper, a probe-fed self-affine fractal antenna, which has a novel configuration, is proposed and investigated for low profile and multi-band performance in wireless communication systems. Fractal antenna is characterized by space filling and self-similarity properties which results in considerable size reduction and multiband operation compared to conventional microstrip antenna. The proposed self-affine rectangular fractal antenna shows multiband behavior due to self-affinity in their geometrical structure. Fractal is implemented on rectangular patch of dimension 40mm x 30mm embedded on ground plane of dimension 60mm x 60mm.The antenna is designed on a substrate of dielectric constant €r=4.4 and thickness 1.6mm. The base antenna is designed and simulated for 2.3 GHz. Further the base antenna is modified to first iteration fractal antenna and then to second iteration fractal antenna. Along with fractal design the EBG structures are also added to the proposed antennas. The antenna with first iteration and EBG is resonating at 1.9 GHz giving a bandwidth of 91 MHz. The antenna with second iteration and EBG shows multiple frequency resonances at 1.27GHz 1.6 GHz, 2.7 GHz, 3.44GHz, and 3.8GHz The antenna with second iteration indicates size reduction of 52.67% and gives over all bandwidth of 259 MHz. The proposed antenna is simulated using IE3D and simulated results are in good agreement with measured results. Keywords: self-affined antenna, Fractal antenna, multi-frequency, size reduction, wireless application. 15 International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 2, March – April (2013), © IAEME I INTRODUCTION The emergence of antennas with fractal geometries has been a very valuable tool for solving two of the major limitations of classical antennas: the single band performance and the dependence of the operating wavelength on size. The self-similar properties of certain fractals result in antenna with fractal properties having multiband behavior. On the other hand, the highly convoluted shape of these fractals makes possible the reduction in size of certain antennas . The most recent multiband antenna development is based upon the exploitation of the self-similarity property of fractal shapes and a number of new antenna designs have been reported in the literature. Fractals are a class of geometrical shapes which have no characteristic size (irregular patterns). These are composed of multiple iterations of a single elementary shape and are used to describe a family of complex shapes that possess an inherent self-similarity and self-affinity in their geometrical structure. A self-similar set is one that consists of scaled down copies of itself, i.e., a contraction which reduces an image by same factors horizontally and vertically. A Self-affine set, on the other hand, is a contraction which reduces an image by different factors, horizontally and vertically. Thus, it can provide additional flexibility in the antenna design, since by selecting the scale factors appropriately; resonances can be spaced by different factors . The space-filling property of fractals tends to fill the area occupied by the antenna as the order of iteration is increased. Higher order fractal antennas exploit the space-filling property and enable miniaturization of antennas . The total volume of multi-resonant structure can be considerably reduced by optimizing the shape of fractal geometries in designing multi- band antennas. Many studies on the complex fractal structure have been carried out rapidly after the concept of fractal geometry, which provides isotropic self-similarities in large or small scales focused on antenna design and appears to be self-affine properties in signal processing and material surfaces has been introduced by Mandelbrot . Method of improving the antenna performance is by using the electromagnetic band gap (EBG) structure on microstrip antenna. EBG structures are periodic lattices, which can provide effective and flexible control over the propagation of the EM waves within a particular band. It has been shown that this structure can lower input return loss and widen the impedance bandwidth by suppressing the unwanted surface waves .This feature applied in field of antennas helps improve performance of antenna, such as increasing the gain of antenna. In this paper we propose self-affine rectangular fractal antenna with first and second iterations. Along with fractal the uniplanar compact electromagnetic band gap (UC-EBG) periodic structures are surrounding the antennas. The study has been made to know the bandwidth, gain and size reduction of proposed antennas. II DESIGN OF SELF-AFFINE RECTANGULAR PATCH ANTENNA WITHOUT EBG Self-affine fractal antenna is considered in this paper which reduces an image by different factors; horizontally and vertically thus it can provide additional flexibility in antenna design. The iteration factor which represents the construction of fractal geometry generation is chosen to be one fourth and iteration number is two. The antenna is designed on a dielectric substrate of relative dielectric constant r=4.4 and thickness 1.6mm. The shape of zeroth iteration is shown in fig 1(a), is a conventional rectangle antenna of dimension 40mm x 30mm is mounted on substrate having a ground plane of dimension 16 International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 2, March – April (2013), © IAEME 60mmx60mm. The multiband antenna with fractal geometry is created by the initial model. The suitable feed location is obtained at (-4mm, -8mm) from the origin through optimization technique. The input impedance of the antenna was calculated using IE3D software package. Fractal geometry of reference and its first and second iterations with scaling factor of four are as shown in figure 1(a) to 1(c). The photographs of base, First and Second iteration antennas are as shown in fig 2(a) to 2(d). Fractal antennas are optimized resulting in the following parameters h=1.6mm, L=40mm, W=30mm, g=60mm,Wg=60mm,L1=7.55mm,W1=10mm,L2=10mm,W2=7.55mm,L3=2.5mm,W3=4. 06mm, L4=4.06mm,W4=2.5mm.Dp=(-4mm,-8mm) The return loss characteristics and radiation patterns of the fractal antenna are as shown in fig: 2 and fig: 3 respectively. Fig 1(a) Fig 1(b) Fig 1(c) Geometry of reference First iteration fractal Second iteration fractal antenna antenna antenna Fig 2(a) Fig 2(b) Fig 2(c) Fig 2(d) Fabricated reference Fabricated antenna Fabricate antenna Fabricated antenna Antenna with top with bottom view with first iteration with second iteration The characteristics of all proposed antennas were simulated by using IE3D software and verified experimentally by using vector network Analyzer model Rhode and schewarz, German make ZVK model No.8651. For all cases, the simulated results obtained and are compared to the experimental results and are shown in fig 3(a) to 3(c). The measured parameters are shown in purple coloured lines while simulated ones are shown in dark block coloured lines. From the figure it is observed that there is a good agreement of simulated results with measured results. Self-affined rectangular fractal antenna with zero iteration is resonating at 2.32 GHz and 3.55GHz. The antenna with first iteration gives resonance at 1.9 GHz. Similarly the antenna with second iteration is resonating at 1.27 GHz, 1.62 GHz, 2.72 GHz, 3.46GHz and 3.82GHz i.e it gives multiple frequencies. The results of proposed fractal antenna with different iterations are shown in Table 1.The overall bandwidth is 245 MHz with second iteration. The radiation patterns of 17 International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 2, March – April (2013), © IAEME all iterations were studied through simulation and it is shown in fig 4(a) to 4(d). All the radiation patterns are broadside patterns. Practical radiation patterns are as shown in fig 5(a) & 5(b). Simulated radiation pattern well agreement with measured results. Fig 3(a) Fig 3(b) Fig 3(c) Return loss characteristic Return loss characteristic Return loss characteristic of of reference Antenna of antenna with first iteration antenna with second iteration Fig 4(a) Fig 4(b) Fig 4(c) Fig 4(d) Radiation pattern Radiation pattern Radiation pattern Radiation pattern @ 2.3 GHz for @ 1.91GHz for @ 1.27GHz for @ 1.6GHz for conventional first iteration second iteration Second iteration antenna antenna without EBG without EBG Table: 1 Results of proposed antennas without EBG Structure 18 International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 2, March – April (2013), © IAEME Fig: 5(a) Fig: 5(b) Practical Radiation pattern H-plane Practical Radiation pattern H-plane copolar at1.91GHz for first iteration Copolar 1.6 GHz for second iteration for First iteration III. DESIGN OF SELF -AFFINE RECTANGULAR FRACTAL ANTENNA WITH EBG STRUCTURE Fig 6(a) to 6(c) shows the geometries of rectangular fractal antenna with EBG structure. Geometry of designed Self-affine rectangular fractal antenna with zero, first and second iterations are surrounded by UC-EBG of Six numbers with size 9mmX9mm.The total area occupied by the base shape patch is 40mmx30mm. The gap between EBG Structures them is 1mm. Optimized dimensions obtained are h=1.6mm, La=40mm,Wa=30mm,Lg=60mm,Wg=60mm, L1=7.5mm, W1=10mm, L2=10mm, L3=2.5mm, W3=4.06mm, L4=4.06mm, W4=2.5mm, Dp= (-4mm, -8mm). The photograph of all designed antenna with self-affine rectangular fractal withUC- EBG are shown in fig 7(a) to 7(c) Fig: 6(a) Fig: 6(b) Fig: 6(c) Geometry of reference First iteration fractal Second iteration fractal antenna with UC-EBG antenna with UC-EBG antenna with UC-EBG cells cells cells Fig: 7(a) Fig: 7(b) Fig: 7(c) Photograph of fabricated Photograph of Fabricated Fabricated antenna with antenna top view with antenna bottom view second iteration UC_EBG first iteration with first iteration structure 19 International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 2, March – April (2013), © IAEME Simulated and measured return loss characteristics of antenna are shown in 8(a) to 8(d). The agreements between measured and simulated results are good. The results are summarized in Table 2.The results indicate that the proposed antenna performance with periodic UC- EBG structures is improved in terms of band width and size reduction. The reference antenna with zero iteration is resonating at 2.32GHz and 3.51GHz. The antenna with first iteration gives resonance at 1.9GHz, while the second iteration is resonating at 1.27GHz, 1.6 GHz, 2.7GHz, 3.44GHz, and 3.8GHz respectively. The overall bandwidth is enhanced to 259 GHz with second iteration. Fig: 8(a) Fig: 8(b) Return loss characteristics of Return loss characteristic of antenna reference antenna UC-EBG with first iteration with UC-EBG Fig: 8(c) Return loss characteristic of second iteration with UC-EBG Table: 2 Results of proposed antennas with UC-EBG structure 20 International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 2, March – April (2013), © IAEME Radiation patterns have been studied for the fractal antennas with UC-EBG structure and it is shown in fig 9(a) & 9(b) all are gives broad side pattern. Measured radiation pattern also shown in fig 10(a) & 10(b) which also gives broadside. The bandwidth of the antenna with first iteration with UC-EBG is 91MHz with corresponding size reduction of 33.34%. Further there is an increment in overall band width of about 259MHz and corresponding size reduction of 52.67% after second iteration. In summery there is increment in overall bandwidth of self-affine fractal antenna with periodic UC- EBG structure in comparisons with self-affine antenna without UC-EBG structure. Fig: 9(a) simulated radiation patterns Fig: 9(b) Simulated radiation pattern of of proposed with first iteration periodic proposed antenna with second iteration UC-EBG structure @1.9GHz periodic EC-EBG structure @ 1.6GHz Fig: 10(a) Practical radiation pattern of Fig: 10(b) Measured radiation of proposed proposed antenna with first iteration with antenna with second iteration UC-EBG Periodic UC-EBG structure @ 1.9GHz structure @ 1.6GHz 21 International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 2, March – April (2013), © IAEME Table: 3 Results shown to compare proposed antennas without and with UC-EBG structure IV. CONCLUSION This paper outlines a new concept of self- affined rectangular fractal antenna with iteration factor of ¼ and order two are applied to fractal geometry with and without UC-EBG structure. Measured value of resonant frequencies and bandwidth of these antennas have been found to agree well with the simulated ones. The Antenna gives multifrequency operations and reduced size. The size reduction obtained is 52.67% with bandwidth of about 259MHz after second iteration. Measured radiation characteristics of proposed antenna with and without UC-EBG are well agreement with simulated radiation characteristics and they are broadside patterns. REFERENCES  C. Borja, G. Font, S. Blanch and J. Romeu “High directivity fractal boundary microstrip patch antenna” ELECTRONICS LETTERS 27th April 2000 Vol. 36 No. 9,pp-778-779.  Sachendra N. Sinha, Senior Member, IEEE, and Manish Jain “A Self-Affine Fractal Multiband Antenna” IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, VOL. 6, 2007, pp- 110,112.  Ananth Sundaram, Student Member, IEEE, Madhurima Maddela, Student Member, IEEE, and Ramesh Ramadoss, Member, IEEE “Koch-Fractal Folded-Slot Antenna Characteristics” IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, VOL. 6, 2007, pp-219-222.  Tae-Hwan Kim, Jae-Wook Lee, Choon-Sik Cho “A CPW-Fed Self-affine Fractal Antenna” IEEE 2005, pp-250-253.  Ban-Leong ooi, Senior Member, IEEE “A Modified Contour Integral Analysis for Sierpinski Fractal Carpet Antennas with and Without Electromagnetic Band Gap Ground Plane” IEEE Transactions on Antennas and Propagation, Vol.52, No. 5, May 2004.  Wei He, Ronghong Jin, Junping Geng, and Guoming Yang “ 2 x 2 Array with UC- EBG Ground for Low RCS and High Gain” Microwave and optical technology Letters, Vol. 49, No. 6, June 2007.  Sanjay V Khobragade and Anitha V R, “Innovative Design of Tree Shaped Fractal Antenna Using Rectangular and Triangular Patches for 2.4 GHZ” International journal of Electronics and Communication Engineering &Technology (IJECET), Volume 3, Issue 1, 2012, pp. 188 - 193, ISSN Print: 0976- 6464, ISSN Online: 0976 –6472.  Jagadeesha.S, Vani R.M and P.V Hunugund, “Stacked Plus Shape Fractal Antenna for Wireless Application” International journal of Electronics and Communication Engineering &Technology (IJECET), Volume 3, Issue 1, 2012, pp. 286 - 292, ISSN Print: 0976- 6464, ISSN Online: 0976 –6472.  Jagadeesha.S, Vani R.M and P.V Hunugund, “Size Reduction And Multiband Operation of Rhombusshaped Fractal Microstrip Antenna for Wireless Applications” International journal of Electronics and Communication Engineering &Technology (IJECET), Volume 3, Issue 2, 2012, pp. 445 - 450, ISSN Print: 0976- 6464, ISSN Online: 0976 –6472. 22
"SELF-AFFINE RECTANGULAR FRACTAL ANTENNA WITH UC-EBG STRUCTURE-2"