Regular paper Wideband Snowﬂake slot antenna using Koch iteration technique for wireless and C-band applications Bappadittya Roy a,⇑ , A. Bhattacharya a , S.K. Chowdhury b , A.K. Bhattacharjee a a National Institute of Technology, Durgapur, India b Jadavpur University, Kolkata, India article info Article history: Received 25 December 2015 Accepted 19 August 2016 Available online xxxx Keywords: Wideband antenna Rectangular feed antenna Koch Snowﬂake slot antenna Fractal antenna abstract A wideband rectangular feed Koch Snowﬂake slot antenna proposed for WLAN/WiMaX applications has been presented in this article. The Snowﬂake slot is introduced at the back of the substrate. With help of CST Microwave Studio Suite TM the proposed structure has been designed and analyzed. The bandwidth of the antenna has been increased by using Koch iteration technique. Results of simulation indicate that the proposed fractal antenna covers an impedance bandwidth of 2.5–6.6 GHz which covers the applica- tion bands of WiMaX and WLAN. The antenna exhibits a gain of 3.6 dBi, 4.5 dBi, 4.7 dBi, 4.6 dBi and 3.9 dBi at frequencies of 2.5 GHz, 3.5 GHz, 5.2 GHz, 5.5 GHz and 5.8 GHz respectively. Ó 2016 Elsevier GmbH. All rights reserved. 1. Introduction In the recent year researchers are developing ultra-wideband (UWB) antenna rapidly because of the advantage of high data rate, low cost and very low power consumption [1]. To achieve wider bandwidth, the various conventional method are used, generally cutting slots in the radiating patch or in ground plane [2–4]. For simplicity of analysis, any geometrical shape patch are used. Among the shapes of the slots, Sierpinski fractal geometry is a spe- cial shape of slot structure that is widely used for bandwidth enhancement. Several examples of using fractal resonant elements like: Hilbert, Minkowski, Gosper etc have been reported earlier. Werner provided a deep overview of fractal antenna in [5]. In [6] Mahdi introduces the penta-gasket-Koch. This design achieves best input impedance throughout the passband, but efﬁciency and fab- rication tolerance is very low in this structure. Microstrip patch antennas are low proﬁle antennas. However, the main disadvantage of these type antennas has low gain and narrow bandwidth [7]. Efforts are in progress to increase the band- width by using various fractal iterative shapes, in combination with either a triangular, fork like or circular tuning stub, optimized for wide-band operation, is found in literature [8–10]. In this work a fractal monopole antenna has been proposed, where the Koch curve was introduced in a ground plane. The radi- ating patch and the feed lines are photo etched on the dielectric substrate. The process, etching in the interior of the radiating ele- ment of a planar monopole is a simple means for creating a fre- quency notch while maintaining the wide-band operation [11– 13]. The proposed structure also covers the wideband frequency range. In this paper Koch Snowﬂake iterative design is employed to enhance the bandwidth of the antenna. Koch fractal geometry was originally introduced by Helge von Koch in 1904. The Koch geometry can be generated using an iterative function system (IFS) represented by a set of ﬁne transformations [14–18]. The basic geometry that is analyzed throughout this paper is the mono- pole antenna apply with Koch fractal boundary. This geometry is obtained by replacing the sides of an equilateral triangle by a Koch curve. In Fig. 1, the Koch island fractal at different iteration stages is shown. At each new iteration n, the area of the island increases. Let S n be the area at iteration n, then the area of the next iteration can be computed as, S nþ1 ¼ S n þ ﬃﬃﬃ 3 p 12 4 9  nÀ1 Â a 2 ð1Þ where a is the side length of the initial triangle that has an area S 0 ¼ ﬃﬃ 3 p 4   a 2 . Simulated S 11 (dB) versus frequency (GHz) plots using three iter- ations are shown in Fig. 2. It is found that the impedance bandwidth is gradually increased with the change of structure from basic iteration to 2nd iteration. For the basic iteration bandwidth (BW) is negligible, for the 1st iteration BW 1.6 GHz and for 2nd iteration we achieve 93.33% of BW(%), where BW is 4.5 GHz.(2.5–6.6 GHz). From the Fig. 2 it will http://dx.doi.org/10.1016/j.aeue.2016.08.010 1434-8411/Ó 2016 Elsevier GmbH. All rights reserved. ⇑ Corresponding author. E-mail address: bappadittya13@gmail.com (B. Roy). Int. J. Electron. Commun. (AEÜ) xxx (2016) xxx–xxx Contents lists available at ScienceDirect International Journal of Electronics and Communications (AEÜ) journal homepage: www.elsevier.com/locate/aeue Please cite this article in press as: Roy B et al. Wideband Snowﬂake slot antenna using Koch iteration technique for wireless and C-band applications. Int J Electron Commun (AEÜ) (2016), http://dx.doi.org/10.1016/j.aeue.2016.08.010