Fractal Antennas For Wireless Applications

Abstract

The wireless revolution is transforming the existing global telecommunications networks into an integrated system that will provide a broad class of ubiquitous communications services to customers anywhere, anytime, in motion or fixed. Antenna is an important device in WLAN communication system because its performance will directly impact on the quality of wireless communications. The continuous shrinking size of electronic equipments demands similar size antenna elements in order to fit properly in wireless devices without compromising the other radiation properties of the antenna. In this respect microstrip patch antennas are quite an obvious choice. This project started by identifying two main disadvantages of the typical microstrip antenna that are the low gain and narrow bandwidth. These two major drawbacks have limited its application despite of other advantages as compared to the conventional antenna. With the purpose of designing a wideband microstrip antenna, the two already proven bandwidth enhancement techniques; the patch stack configuration and coplanar parasitic patch was studied. Several antenna configurations were proposed and from the simulation result, the antenna bandwidth was improved from the typical 8 ~ 9 % up to 36 % by using these two techniques using a simple coaxial probe feeding without any matching network. A microstrip patch antenna consists of radiating patch placed on the dielectric material. The feed line is sandwiched between the two substrates in proximity feeding technique. The different types of slots on the patch and the stacking help in increasing the bandwidth and give the efficient results. In this thesis report various antenna designs are given and then study the various effects of different parameters like patch length, patch width, substrate height, and dielectric constant for WLAN applications. The antennas are designed using CST 2010 microwave studio. The antenna parameters like return loss, bandwidth, resonating frequency, directivity, gain and VSWR are calculated for each antenna design in order to get the best antenna.