Design and Development of Multiband Fractal Antenna for Wireless Applications

Abstract

In today’s world, the antenna designing plays the major role in design and development of any wireless communication system. In the current scenario, there is a huge demand of both wideband and multiband microstrip patch antennas for various wireless applications. There are number of techniques that can be useful for reducing size and making antenna multiband and wideband which include making use of fractal geometry, use of slot and DGS. In this report, An X shaped patch antenna has been designed and fractal geometry has been applied in order to obtain self-similar characteristics. Different iterations have been carried out to achieve required bands. X shape is simpler in design as compared to traditional fractal shapes of Koch curve, Sierpinski carpet etc. Initially an X shaped fractal patch with a dimension 108 mm X 88 mm having ground plane of width 20 mm has been designed. FR4 is used as the substrate material having thickness of 1.6 mm. This antenna can operate over the frequency range of 5.2 GHz to 7 GHz. Thus, showing the wideband characteristics. Further in the thesis, use of Defected Ground Structure (DGS) in reducing the total size of antenna is shown by cutting two vertical I shaped slots in the ground plane and varying the width of ground plane. Parametric analysis of various parameters like no of slots, slots length, width of ground plane, substrate material and feed line length has been carried out in order to optimize the results. From parametric analysis we finally obtained two antennas. First is reduced version of initially proposed antenna having same wide band characteristics with percentage bandwidth of roughly 28.8 percent and dimensions of 94mm X 88 mm. Thus, there is net 13 percent reduction in size. Antenna resonates at four bands of 3.6 GHz, 5.5 GHz, 5.95 GHz and 6.5 GHz. This antenna has good directivity of 4.36dBi, 7.13 dBi, 5.52 dBi and 5.55dBi. This antenna covers various applications like WiFi bands (IEEE802.11a), Fixed satellite radio transmission, vehicular communication systems (IEEE802.11P), licensed band (IEEE802.11y), cordless telephony. Second is having multiband characteristics and it resonates at four bands of 2GHz, 3.5GHz, 4.9GHz, 6GHz. This antenna has good directivity of 3.23dBi, 4.3dBi, 5.95dBi, 6.5dBi respectively. This antenna covers various applications like Public safety WLAN, WiMAX applications, Earth to space communication and future 5G telecommunication.