Design and Analysis of Effect of Parasitic Patch on Fracta Antenna

Transcription

1 International Journal of Electronics and Computer Science Engineering 686 Available Online at ISSN: Design and Analysis of Effect of Parasitic Patch on Fracta Antenna Akhilesh Kumar 1, Aadesh Kumar Arya 2 and Reshu Gupta 3 1 PG Student, 2 Department of Electronics Engineering, Shobhit University, Meerut, India 3 Department of ECE, Rajkumar Goel Institute of Technology for Women, Ghaziabad, UP, India Id: akhilesh48@gmail.com Abstract- With the rapid development of wireless communication systems, the multiple separated frequency bands antenna ha become one of the most important circuit elements and attracted much interest. In order to satisfy the IEEE WLAN standards and the worldwide interoperability for microwave access (WiMAX) bands, various antennas for wide band operatio have been studied for communication and radar systems. The design achieves a good input impedance match and linear phase o S11 throughout the pass band (1.5 7 GHz and-10 db criterion for impedance bandwidth).). The use of fractal pattern in thi paper provides a simple and efficient method for obtaining the compactness. The gain of antenna is enhanced by using parasiti patch. Various bands are 1.66GHz, GHz, GHz, GHz, GHz, 12.10GHz and GHz. The maximum directivity of the antenna is dbi and the VSWR is between 1 and 2. This antenna is suitable for applications in ICMS DECT, UMTS, Bluetooth and WLAN systems. Because of linear phase and good impedance match, with some furthe optimization and manufacturing aspect, this antenna can serve in UWB and wireless USB applications. Keywords:- multiband antenna, fractal, Minkowski, high gain antenna, WLAN antenna, parasitic patch 1. Introduction The current upsurge in wireless communication systems has forced antenna engineering to face new challenges, whic include the need for small-size, high-performance, low-cost antennas. Miniature antennas are of prime importance due to th available space limitation on the devices and the oncoming deployment of diversity and multiple-input multiple-output (MIMO systems. The basic antenna miniaturization techniques can be summarized into lumped-element loading, material loading, th use of ground planes, short circuits, the antenna environment, and, finally, geometry optimization [1]. Among these techniques geometry optimization and the use of ground planes can achieve miniaturization while maintaining good antenna performance especially in terms of bandwidth and efficiency [2]. The main objective of this paper is to design a square shaped fractal antenna which will be small in size and for multiban operation with high gain and enhanced bandwidth. For gain and bandwidth enhancement a parasitic patch is used (Figure.1). F reducing the size of antenna, fractal geometries have been introduced. Figure.1.A square microstrip patch with parasitic patch Euclidean geometries are limited to points, lines, sheets & volumes, Fractal include geometries that fall in between these distinctions.therefore, a fractal can be line that approaches a sheet. These space filling properties lead to curve that are electrically very long, but fit into a compact physical space. This property leads to miniaturization of antenna elements. Fractals could be used to define the spacing in arrays for thinning or to define radiation pattern. With successive iteration the length of Minkowski curve increases by 1/3 of the original length. Length of Minkowski after nth iterations: L N = (4/3) n x Lo.... (1)

2 IJECSE,Volume1,Number 2 Akhilesh Kumar et al. L N and Lo are the length after nth iteration and original length (without any iteration) respectively. For Minkowski fractal with each iteration the area of the holes and circumference of solid pieces changes. In Section II, the fractal Minkowski antenna is described and its input parameters are shown. Both numerical and experimental results show that as the number of iterations in the monopole increase, the of the antenna approaches the fundamental limit for small antennas. 2. Proposed Antenna Design The proposed antenna is designed by using concept of Minkowski fractal structure, which originates from the plan square patch and subsequent fractal antenna. Minkowski iterations produce a cross-like fractal patch with even more fin details at the edges. The antenna is designed by using the square patch and iterating first iteration at the center of each side. Iterate polygons (indentation) in the shape of rectangle are created. The square patch fractal antenna is based on Minkowski squar shaped. For designing this fractal antenna IE3D software is used which is based on method of moment (MoM). The FR 4 material is used as substrate. The thickness of the substrate is mm (d 1 ). The dielectric constant (ε r ) of the antenna i 4.3. The Minkowski fractal shape is used in this paper with two iterations. In decomposition algorithm for rectangular shape i cut down from each side of the square patch antenna which shows the 1st iteration and generates two resonance frequencies To design the fractal antenna a square shape structure is designed on the simulator. Rectangular indentation is cut down from the each side of the square. Figure 1 shows the square patch antenna withou iteration and Figure. 2 shows the fractal with 1st iteration of the square patch antenna. The side length of square patch fracta antenna is 30 mm (without iteration) and after iteration indentation size is 2 8 mm and square size is 14 mm. For 2n iteration the indentation size 1 4 mm is cut down from every square. Figure 3 shows the square patch fractal antenna wit second iteration and generate multiple resonant frequencies. According to Falconer since the generator used to develop the proposed structure involves similarity transformations of mor than one ratios a1 and a2. The dimension, d, is a solution to the following equation: Where d represents the dimensions, a1 is the ratio W 1 /L 0 and a2 is the ratio of W 2 /L 0. Then according to equation (2) when a1, a2 or both are varied, then fractal structures with different dimensions may result in. The length of the antenna i L (initially) and the geometrical object obtained at the first iteration. For determining the dimension of self-simila deterministic structure, like the geometries in this article, the self-similar dimension provides an intuitive approach. After 1st iteration the fractal antenna has four squares of same size. Each square has side length 14 mm. After 2 n iteration the fractal antenna has twelve squares of same size each has side length 6.5 mm. Figure.2 Proposed driven patch with Zero, 1 st and 2 nd Iterations It is observed that as the resonant frequencies and gain of loop is decreased as the generating iterations is increased. Th next step is to improve the bandwidths of the dual-band narrowband antenna. A technique based on a dual stacked parasiti element is used. By choosing carefully the resonant frequency of the parasitic element and the coupling with the driven patch the bandwidth can be optimized [8]. To adjust the size, distance between the driven and the parasitic elements, and the positio of the feeding point, an iterative process is followed [8].According to [8], to place the impedance loops at the centre of th Smith chart, a high impedance feeding point is required, as well as having a parasitic patch that resonates at the sam frequency as the driven element. The reason of feeding the driven at a high-input impedance point is that parasitic patch move

3 Design and Analysis of Effect of Parasitic Patch on Fractal Antenna impedance to lower impedances. Here in this paper a square parasitic patch [8] of 62 mm (L2) at a height of mm (d2) with a dielectric constant of 1 Figure.3 Antenna geometry variations Figure 4. Minkowski (2 nd patch antenna with parasitic patch 3. Result and Discussion The simulated results of input return loss for 1st iteration are shown in Figure.5. The return losses are db, db, db, db, db, db and 22 db for the resonance frequencies 1.66GHz, GHz, GHz GHz, GHz, 12.10GHz and GHz. The bandwidth of the antenna is is 50 MHz, 891 MHz, 1065 MHz, 181 MHz, 184 MHz and 355 MHz respectively for 2nd iteration along with parasitic patch. The gain of the antenna is generall greater than 4 dbi with a peak gain of 5.8 dbi. The gain of antenna at different frequencies is shown in Figure.7. The directivit of proposed MFA(Minkowski Fractal Antenna ) is generally greater than 10dBi with a peak directivity of dbi. Th directivity of antenna at different frequencies is shown in Figure.8. The azimuth radiation pattern of MFA is presented i Figure.9. Table.1.Comparative analysis of different operating bands after parasitic patch Operating Microwave Bands IEEE Standards Resonant Frequency Return Loss 10 db Bandwidth With Parasitic Patch fo (GHz) db f L (GHz) f H(GHz) (f H-f L) MHz Efficiency(%) Gain(dBi) L <0 S <0 C <0 Without Parasitic Patch Gain(dBi) X Ku

4 Figure.5. Simulated reflection coefficient (S 11 in db) characteristics of planar Minkowski Fractal antenna ( 2 nd Figure.6. Simulated reflection coefficient (S 11 in db) characteristics of planar Minkowski Fractal antenna (1 st Figure.7. Gain characteristic of FMA antenna with parasitic patch(2 nd Figure.8. Gain characteristic of FMA antenna without parasitic patch(2 nd

5 Figure:9. Directivity characteristic of FMA antenna (2 nd Figure:10. Efficiency characteristic of FMA antenna (2 nd Figure:11.Current distribution of proposed antenna at different resonant frequencies 4. Conclusion The resonance behavior and space filling capabilities of the Minkowski based square patch fractal antenna have been investigated. It is found that as the resonant frequencies and gain of loop is decreased as the generating iterations i increased. By introducing a parasitic patch at a specific height and specific dimension improves the antenna gain as well as it bandwidth. The frequency band of antenna is lies between 2GHz to 4 GHz (WiMax, WiFi, ISM, DECT) and 6 GHz to 12 GH ( UWB, Wireless USB, X-Band). The parasitic patch is needed to improve gain and bandwidth. The gain, return loss and bandwidth of proposed FMA is similar to the antenna explained in Novel Wideband Plana Fractal Monopole Antenna [4].

6 References [1]. A.K. Skrivervik, J.-F. Zurker, O.Staub, and J.R. Mosig, PCS antenna design: The challenge of miniaturization, IEEE Antennas Propagat Mag 4 (2001), [2]. H. Morishita, Y. Kim, and K. Fujimoto, Design concepts of antennas for small mobile terminals and the future perspective, IEEE Antennas Propaga Mag 44 (2002), [3]. Cohen, N. (Summer 1995). "Fractal Antennas". Communications Quarterly: 9. [4]. Mahdi Naghshvarian-Jahromi, Novel Wideband Planar Fractal Monopole Antenna, IEEE Transaction on antennas an propagation, pp , 56 (12), [5]. M. Comisso, Theoretical and Numerical Analysis of the Resonan Behaviour of the Minkoviski Fractal Dipole Antenna, IET Microwav Antenna and Propagation, 3pp , [6]. John P. Gianvittorrio and Yahya Rahmat-samii, Fractal Antennas: A Novel Antenna Miniaturization Technique and Applications, IEEE Antenn and Propagation Magazine, pp , 44 (1), [7]. N. Telzhensky and Y. Leviatan, Novel method of UWB antenna optimization for specified input signal forms by means of genetic algorithm IEEE Trans. Antennas Propag., vol. 54, no. 8, [8]. J. Anguera, C. Puente, and C. Borja, Procedure to design electromagnetically coupled microstrip patch antennas based on a simple network model Microw. Opt. Technol. Lett., vol. 30, no. 3, pp , Aug [9]. Balanis C.A., Antenna Theory: Analysis and Design, Second Edition, New York, John Wiley& Sons, Inc., [10]. Baharav Z., Fractal Arrays Based on Iterated Function Systems (IFS), IEEE Int.Symp. On Antennas and Propagation Digest, Florida, Vol. 4 pp ,1999. [11]. Bamsley M.F., Fractals Everywhere, Second Edition, Academic Press Professional, New York, 1993.