Design, Fabrication And Performance Evaluation Of Dual And Triple Band Microstrip Patch Antennas With Microstrip Feeding For Wireless Applications

Abstract

The existing global telecommunication networks are being transformed by wireless revolution into an integrated system that will provide a broad class of ubiquitous communications services to customers anywhere and anytime. Antenna is an important device in every 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 device without compromising the other radiation properties of the antenna. In this respect microstrip patch antennas are quite an obvious choice. Microstrip antennas have numerous advantages such as small size, low fabrication cost, light weight and can be easily installed in the system and it finds its applications in various systems like aircraft, satellite and spacecraft. But it has drawback of narrow bandwidth. To overcome this drawback, Microstrip antenna with Defected Ground Structure can be used. In this thesis work presented, Transmission line model is used to simulate Microstrip patch antenna using Microstrip line feed. The aim is to study the effect of antenna dimensions Length (L), Width (W), and the substrate parameters relative Dielectric constant (єr). Low dielectric constant substrate parameters are generally preferred for maximum radiation. Next, various Microstrip antennas for different WLAN/Wi-MAX and STM link applications with DGS (Defected Ground Structure) are presented with a dual band and triple band. The various parameters like return loss, smith chart, radiation pattern and VSWR etc have been studied and plotted for each simulated antenna. A triple band antenna has been achieved in the first design. The first band has resonant frequency 5.5 GHz and bandwidth is 66 MHz with return loss -12.95. This frequency range is used for Wi-MAX applications. The resonant frequency of second band is 6.3 GHz and bandwidth is 190 MHz with return loss -30.56. The third band has resonant frequency 6.8 GHz and bandwidth is 102 MHz with return loss -16.72. This second and third band is suitable for wireless application of STM link 1 (Synchronous Transport Module level 1). Later, a dual band microstrip patch antenna with Defected Ground Structure (DGS) and Microstrip feeding technique has been designed, simulate and analyzed. The first band has resonant frequency 4.9 GHz and bandwidth is 175 MHz with return loss -12.75 dB. The resonant frequency of second band is 7.6 GHz and bandwidth is 159.8 MHz with return loss -13.01 dB. Another dual band microstrip patch antenna with Defected Ground Structure (DGS) and microstrip feeding technique has been designed, simulated on CST Microwave Studio 2010 Software and analyzed. A dual frequency band is achieved through this design at resonant frequencies 4.3 GHz and 5.9 GHz. The return loss for 4.3 GHz is -20.6 dB and the return loss for 5.9 GHz is -14.46 dB which covers the minimum required value of return loss of -10 dB. These frequency bands find their applications in Wi-MAX and WLAN respectively. The affects of various parameters like length of the feed, width of the feed and also of slot, and slot position in case of Microstrip line feed has been presented. Finally, a fabrication procedure has been done on the proposed triple band antenna design and the measured results are compared with simulated ones to validate the antenna performance in practical scenario.