Design of an Improved X-Shaped Fractal Antenna With Defected Ground Structure

Abstract

Today's modern communication system is challenging the antenna designers to design compact and portable antennas that have ability to meet multi standards. Fractal geometries are widely used in antenna design because of their unique properties of self-similarity and space-filling. In this thesis, the fractal geometry has been applied to Microstrip patch to design the antenna for wireless applications. Effect of each parameter used in designing of the antenna on its performance is discussed by varying each parameter separately. Importance of fractal iterations in decreasing the fundamental frequency and increasing the number of resonating bands is illustrated by comparing the results of each stage including the initiator path also. Microstrip feed line is used for the excitation of antenna. Defected ground structure (DGS) is also applied on the conventional ground to improve the radiation characteristics which is depicted by the return loss plots with and without DGS. Antenna is designed and fabricated on the FR-4 substrate having dielectric constant of 4.4. All the simulations are performed on CST (Computer simulation technology) software. Finally, a multiband antenna is formed that confirms its applications in many wireless standards of modern communication system. The operational resonating frequencies comes out to be 1.7 GHz , 2.5 GHz, 3.4 GHz, 4.6 GHz, and 5.5 GHz which can be satisfactorily used for GSM 1700, Bluetooth, IMT, WiMAX and WLAN standards. All the measured results are in agreement with the simulated ones.