A Coplanar FED Slotted Antenna for Multiband Applications

Abstract
A Compact and geometrically low profile multiband microstrip coplanar antenna exclusively used for wide range of wireless applications like Wi-Fi, Wi-Max, WLAN, RADAR, RFID Reader, XWAV, Hiper LAN2,etc….,is proposed. A basic rectangular microstrip patch fed by microstrip feed line forms iteration 0 structure. Over that iteration 1, 2 and 3 are made by adding successive squares at each corners of the previous iteration with coplanar feeding. Radiation characteristics of proposed antenna are simulated using mentor Graphics IE3D Simulator. Its radiation characteristics such as Return loss, VSWR, Elevation pattern, Azimuth pattern, Gain, Directivity, Efficiency etc…, are analyzed and compared.
Keywords: Fractal, IE3D, Wi-Fi, Wi-Max.
I.Introduction
To meet the current trends in the field of modern communication systems, it is essential to design a compact antenna which suits for different wireless applications. Fractal antennas [6-8] are the best suitable radiating structure. Fractal is a new class of geometry that was proposed by “Mandelbrot‟. The physical construction of the fractal is not possible only objects with a limited number of iterations can be built. These objects are usually referred to as pre fractals. These Fractal increases the electrical length of the antenna without affecting the radiation characteristic of conventional antenna [5]. Self similarity and Space filling properties of fractal antennas is utilized in the design of antennas with notable characteristics like multiband behaviour and miniaturization. Self similarity means that an object is build of sub units and sub units on multiple levels which tries to figure out the structure of entire object. Space filling means it uses long electrical length into small dimensions [9-11]. Sierpinski carpet antenna based on fractal geometry is low profile antennas, moderate gain and can be operated at multiband of frequencies leads to a multi functional structure. This type of wideband antenna displays high self similarity and symmetry.
ANTENNA DESIGN
The basic structure of Sierpinski antenna is built from a regular Microstrip patch [2] and runs through several iterations to generate multiband characteristics. The basic structure of the square patch is 54x54mm2as shown in Fig1. The substrate thickness is 1.6mm, the loss tangent is 0.02 and the material used for the antenna is FR4 with dielectric constant 4.4[8]. The coplanar feeding method was used.