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Progress In Electromagnetics Research Letters, Vol. 22, 71–81, 2011

A STACKED EQUILATERAL TRIANGULAR PATCH ANTENNA WITH SIERPINSKI GASKET FRACTAL FOR WLAN APPLICATIONS J. Malik and M. V. Kartikeyan Millimeter Wave Laboratory Department of Electronics and Computer Engineering Indian Institute of Technology, Roorkee 247667, India

Abstract—In present work, a microstrip Sierpinski modified andfractalized antenna using multilayer structure to achieve dual band behavior for WLAN applications has been proposed. Due to the space-filling properties of fractal geometry, the proposed antenna is smaller in size than the conventional Euclidean-type. An equilateral triangular patch antenna with Sierpinski Gasket fractal shape has been designed and studied. An electromagnetic coupled stackedstructure of two different patches operating at two frequencies (2.4 GHz Bluetooth and 5.8 GHz Wireless LAN) has been designed for dual band WLAN applications.

1. INTRODUCTION In recent years, as the demand of portable systems have increased, low profile systems have drawn much interest for researchers. In making such low profile communication systems, the size of the antenna is critical. Microstripantennas are very popular due to their properties, such as low profile, low cost, conformability and ease of integration with active devices. To the growing demand of MMIC (monolithic microwave integrated circuits) compatible antennas, patch antennas are good solution. To integrate these antennas in MMIC circuits for wireless communication applications the size of these microstrip antennas should beas small as possible without compromising on their performance. Therefore, many kinds of miniaturization techniques,
Received 23 December 2010, Accepted 1 February 2011, Scheduled 25 March 2011 Corresponding author: M. V. Kartikeyan (kartik@iitr.ernet.in).

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such as using high dielectric substrates [1], applying resistive or reactive loading [2], increasing theelectrical length of the antenna by optimizing its shape [3], use of notches and short circuits on the patch antenna [4], use of magnetic substrates [5] have been proposed and applied to microstrip patch antennas. Techniques to achieve dual band operation of microstrip antennas are also available [6–9]. The application of fractal geometry to conventional patch antenna structures modifies the shape ofthe antennas in order to increase its effective electrical length at the same time reducing their overall geometrical size. Because fractal geometries have two main features in common, space-filling and self-similar properties, fractal shape antenna elements present various advantages like wide bandwidth, multiband [10, 11], and reduced antenna size, among others. Sierpinski fractal geometry exhibitswell-known features that have been used to construct miniaturized radiating patches either monopole or dipole antennas. By applying the Sierpinski fractal shape to the antennas, the overall electrical length of the antennas increases and the resonance frequency becomes lower than that of conventional monopole, loop, and patchtype antenna. In the present work, Sierpinski Gasket fractal geometryhas been applied to an equilateral triangular microstrip patch antennas to reduce its overall size, and the effectiveness of this technique is verified through experimental investigations. It is found that as the iteration number increases, the resonance frequencies become lower than those of the zero iteration, which represents a conventional equilateral triangular patch. In other words, microstrippatch antennas employing Sierpinski Gasket fractal geometry can operate at a much lower frequency range while maintaining an identical overall antenna size. An electromagnetic coupled stacked structure to operate at two different frequencies (2.4 GHz Bluetooth and 5.8 GHz Wireless LAN) has been designed for dual band WLAN applications. 2. ANTENNA GEOMETRY The antenna configuration of proposed...
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