Browsing by Author "Ahmed, Mohamed Shihab"

Microstrip patch antennas have been the most common type of antennas since it was introduced. Microstrip patch antennas attracted the researchers and industry developers due to their small size, low power consumption, low cost, light weight and portability. Ultra-wideband (3.1 GHz – 10.6 GHz) systems are growing more interest in the present days due to their large capacity, ability to integrate with ICs, low power consumption, and security. Ultra-wideband can be exploited for several applications in communications systems, vehicular radars and imaging systems. The existence of other systems such as Worldwide Interoperability for Microwave Access (WiMAX) that operates in the frequency range (3.3 GHz – 3.6 GHz) and Wireless Local Area Network (WLAN) which operates in the frequency range (5.15 GHz – 5.825 GHz), causes interference with the Ultra-wideband systems. To avoid the interference, band-notched Ultra-wideband microstrip antennas were proposed. The proposed antennas in this dissertation have operational bandwidth that covers the Ultra-wideband with band rejection characteristics for WiMAX and WLAN. The band notches were achieved by engraving a nested inverted U and W shaped slots on the patch. A parametric sweeping study was performed on the proposed designs to determine the optimum dimensions using CST Microwave Studio. The antennas were fabricated on FR4, RO3003, RO4003C and RT5880 laminates. The return loss measurements were obtained from the fabricated antennas using Agilent N5230A PNA Network Analyzer. The return loss measurement results shows that the fabricated antennas using FR4, RO3003 and RT5880 substrates had a noticeable shift in the achieved bands compared to the simulated return losses. However, the antenna fabricated on a RO4003C substrate achieved a bandwidth from 3.05 GHz to 12.77 GHz and rejected bands from 3.27GHz to 3.74 GHz and from 5.16 GHz to 5.96 GHz. Therefore, it is proven from the validation process that RO4003C based antenna is a good candidate for UWB applications.