Bandwidth Enhancement of Microstrip Fed Koch Snowflake Fractal Slot Antenna Venu Adepu Asst Professor, Department of ECE, Jyothishmathi Institute of Technological Science,TS, India Abstract This paper presents a microstrip line fed fractal slot antenna. Koch snowflake fractal slot are used as a resort to achieve bandwidth enhancement. By increasing the iteration order (IO), the bandwidth can be significantly broaden. Both simulation and measurement are consistent with this theory. The structure of the proposed antenna is shown in Figure 1. The dimensions of the geometry are given in the Table 1. For better performance, the thick bandwidth and better radiation. Hence, the substrate of thickness 3.2 mm and with low permittivity ( r = 1.0006). Keywords microstrip line, frctal antenna, Koch snowflake, bandwidth enhancement, iteration order(io) INTRODUCTION Recently, broadband antennas have been widely discussed to meet the requirement for wireless communication system. Werner and Ganguly [1] has provided an overview of fractal antenna. Those fractal structures includes : Sierpinski gasket, Koch snowflake, ternary fractal tree, Hilbert curve, and so on. Chen[2] has discussed the relation between the bandwidth, and iteration order (IO) and iteration factor (IF) of a fractal antenna. IO and IF can characterize shape. However, [2] only provides one data for IF = 0.3. This paper focuses on IF=3, and discusses the bandwidth enhancement increased by IOKOCH SNOWFALKE ANTENNA Fig. 1-4 show Koch snowflake antennas for IO=1, 2, 3, and 4. Fig. 2 shows the feeding microstrip line. Thickness h = 1.6 mm, L = 35 mm, 4.4 r, the width of microstrip line is 3 mm, and the size of this antenna is 70 mm 70mm. The simulation results of an FEM solver are shown in Fig. 3. Choose -10 db as the definition for bandwidth. For IO = 0, the bandwidth (BW) is 0.68 GHz (4.77-5.45 GHz), IO=1, BW = 2.5 GHz (3.12-5.62 GHz), IO = 2, BW = 2.8 GHz (3.07-5.87 GHz), and IO = 3, BW = 2.9 GHz (2.85-5.75 GHz). Table 2 lists the bandwidth percentage for IO = 0-4, For IO increases from 0 to 4, BW(%) increases from 13.3% to 67.44%. From the simulation results, it is obvious that the bandwidth will increases with IO. The simulation will stop at IO = 3, because it is hard to fabricate antenna precisely in the Lab. for IO is greater than 3The structure of the proposed antenna is shown in Figure 1. The dimensions of the geometry are given in the Table 1. For better performance, the thick 1.0006). The dimensions of thethe structure of the proposed antenna is shown in Figure 1. The dimensions of the geometry are given in the Table 1. For better performance, the thick dielectric substrate having a low dielectric constant is required for IJESAT Mar-Apr 2016 1
providing a better efficiency, larger bandwidth and better radiation. Hence, the substrate selected for the design of the proposed antenna is air of thickness 3.2 mm and with low permittivity ( r = 1.0006). The dimensions of the MEASUREMENT AND SIMULATION RESULTS Fig. 2 The feeding microstrip line to fractal slot antenna. Fig. 4 show the measurement results of 11 S. Table II lists all the related values. The measurement results match well with simulation results. One of those test board is shown in Fig. 8 (IO = 3). If the antenna is laid on xy-plane, and microstrip line is fed from x-direction, the related radiation patterns are shown in Fig. 9-12. For xz-plane, the main component is E for f = 3.18 and 4.3 GHz; For yz-plane, the main component is E. The radiation patterns are similar to a monopole antenna. It is quite fascinating that this Koch snowflake fractal IJESAT Mar-Apr 2016 2
antennas can maintain omni-directional properties in a wide frequency range. The structure of the proposed antenna is shown in Figure 1. The dimensions of the geometry are given in the Table 1. For better performance, the thick 1.0006). The dimensions of thethe structure of the proposed antenna is shown in Figure 1. The dimensions of the geometry are given in the Table 1. For better performance, the thick dielectric substrate having a low dielectric constant is required for providing a better efficiency, larger bandwidth and better radiation. Hence, the substrate selected for the design of the proposed antenna is air of thickness 3.2 mm and with low permittivity ( r = 1.0006). The dimensions of the IJESAT Mar-Apr 2016 3
broadband antennas have been widely discussed to meet the requirement for wireless communication system. Werner and Ganguly [1] has provided an overview of fractal antenna. Those fractal structures includes : Sierpinski gasket, Koch snowflake, ternary fractal tree, Hilbert curve, and so on. Chen[2] has discussed the relation between the bandwidth, and iteration order (IO) and iteration factor (IF) of a fractal antenna. IO and IF can characterize shape. However, [2] only provides one data for IF = 0.3. This paper focuses on IF=3, and discusses the bandwidth enhancement increased by IOThe article presents a structure of human shape microstrip patch antenna operating at dual frequencies. In this paper a rectangular patch of human shape cutting is proposed. The human shape antenna is designed for wireless applications, which works at 2.4 GHz and 5.4 GHz frequencies. This proposed antenna can be widely used for Wi-Fi (IEEE 802.11 standard), BLUETOOTH, WLAN, WiMAX (IEEE 802.16 and 802.20 standards. Radio Local Area Networks (RLAN), Fixed Wireless Access Systems (FWA) and NLOS applicationsthe microstrip patch antenna is one of the most preferred antennas due to its compact shape, light weight, less complexity, easy to implement and conformability. The microstrip patch antennas radiate primarily because of the fringing fields between the patch edge and the ground plane [1]. In recent years the demand for the design of dual band, tri-band [2] or multiband antennas is increased, as these antennas can integrate more than one communication standards in a single compact system. Fast development of technology of wireless access to Internet and requirements of standards imposed on WLAN, WiMAX [3] and other technologies of wireless networks entourage demand for equipment which is not only reliable and functional but also is characterised by small size. As antenna is essential element of each wireless system it also has to be miniaturized as well as enable work in more than one frequency strip. This article presents Human shape microstrip antenna which operate at two frequencies 2.4 GHz and 5.4 GHz [4]. The IEEE 802.11b and 802.11g standards utilizes 2.4 GHz ISM band [5]. The frequency band is license-free, hence the WLAN equipment will suffer interference from microwave ovens, card less phone, Bluetooth devices and other appliances that use this same band [6]. The 802.11a standard uses the 2.4 GHz band which supports high-speed WLAN [7]. 5.4 GHz wireless antennas are perfect to use IEEE 802.16 and 802.20 standards. These standards are used for Wi-Fi Systems, Radio Local Area Networks (RLAN), Fixed Wireless Access Systems (FWA), WiMAX Technology and NLOS applications [8]. The structure of the proposed antenna is shown in Figure 1. The dimensions of the geometry are given in the Table 1. For better performance, the thick 1.0006). The dimensions of the CONCLUSIONS A microstrip fed snowflake fractal slot antenna is discussed in this paper. By increase IO from 0 to 4, the bandwidth can be increased from 13.78 % to 67.56 % (measurement). Both simulation and measurement match well. This kind of antenna exhibits omnidirectional properties during a wide frequency range. REFERENCES *1+ D. H. Werner and S. Ganguly, An overview of fractal antenna engineering research, IEEE Antenna and Propagation Magazine, vol. 45, no. 1, pp. 38 57, Feb. 2003. [2] W. L. Chen, G. M. Wang, and C. X. Zhang, Bandwidth enhancement of a microstrip-line-fed printed wide-slot antenna with a fractal-shaped slot, IJESAT Mar-Apr 2016 4
IEEE Transactions on Antennas and Propagation, vol.57, no. 7, pp. 2176-2179, July. 2009. [3] C. A. Balanis, Antenna Theory, 2nd edn., Wiley- Interscience, 2005. IJESAT Mar-Apr 2016 5