IOSR Journal of Electronics and Communication Engineering (IOSR-JECE) e-ISSN: 2278-2834,p- ISSN: 2278-8735.Volume 11, Issue 3, Ver. I (May-Jun .2016), PP 29-32 www.iosrjournals.org DOI: 10.9790/2834-1103012932 www.iosrjournals.org 29 | Page Reconfigurable Koch Loop Fractal Antenna Using RF Switch Kumari Mamta 1 * and Raj Kumar Singh 2 1 Department of Applied Physics, Cambridge Institute of Technology, Ranchi 835103, India 2 Department of Physics, R. L. S. Y. College, Ranchi University, Ranchi, Ranchi 834001, India Abstract: A new reconfigurable koch loop fractal antenna model has been proposed and its properties discussed using HFSS software. The Patch version was figured using the first order Koch loop. By introducing patches of koch loop shapes, the antenna with different radiation patterns were formed using RF switches to switch between the configurations. The radiation pattern has been reconfigured. The proposed antenna will examine the reconfigurability of Koch loop for different resonant frequency. Keywords: reconfigurable antenna, fractal antenna, Koch loop shape, RF switch. I. Introduction The rapid expansion of wireless technology during the last years has led to increase in demand for small size, low-cost and multiband antennas for use in commercial communications systems. Fractal antenna [1] is one such category. These are composed of multiple iterations of a single elementary shape. They are used to describe a family of complex shapes that possess an inherent self-similarity and self-affinity in their geometrical structure. Such as Sierpinski fractal antenna, tree-shaped fractal antenna, snowflake fractal antenna, Koch fractal antenna etc. The Koch fractal loop is one of the most well-known fractal shapes. Swedish mathematician Helge von Koch proposed the Koch curve in 1904 [2]. If Koch generator is applying to an equilateral triangle, after infinite iterations, a Koch snowflake structure is obtained which is smaller than other patch geometries [3]. Though these antennas reduce the size and cost, but in case of communication system many applications are used that works at different frequency band hence a single fractal antenna cannot be used to serve the purpose of the whole communication system. To resolve this issue reconfigurable antennas have been proposed. These antennas resonate at different frequencies at different time by using switches. They have remarkable characteristic of achieving diversity in operation, meaning that one or multiple parameters, including operating frequency, radiation pattern, gain and/or polarization, can be reconfigured a single antenna [4]. Compared to conventional antennas, reconfigurable antennas provide the ability to dynamically adjust various antenna parameters. By means of switches with compatible antenna elements the antenna and its feed structure can be physically reconfigured to provide radiation pattern, frequency band and polarization diversity so they have more advantage to compare with conventional antennas [5]. The most prevalent implementation about reconfigurable antenna is related to the operation frequency [3] since it might be the easiest feature to alter. Polarization and pattern reconfigurable antennas are also attractive since they can provide diversity features which leads to an increased signal to noise ratio and therefore a higher quality of service of whole systems [6-8]. The approach adopted in this paper combines koch loop fractal geometry and reconfigurability in order to come up with a new antenna design suitable for several wireless applications. This will help obtain a resonance at a lower frequency without increasing the overall antenna dimensions. II. Fractal Geometries Fractals are all around us. Fractals are self-similar objects and possess structure at all scales. Two examples of naturally occurring fractal geometries are snowflakes and boundary of geographic continents. Several naturally occurring phenomena such as lightning are better analyzed with the aid of fractals. One significant property of all these fractals is indeed their irregular nature. Some examples of fractals are given in Fig. 1.1.