| Ultra wide-band (UWB) technology is considered one of the very promising wireless technologies in the new millennium. This increases the demand on designing UWB antennas that meet the requirements of different UWB systems. In this dissertation, different UWB antennas are proposed such as an antenna that covers almost the entire UWB bandwidth, 3.5--11 GHz, as defined by the federal communication commission (FCC). This antenna has a size of 50x40x1.5mm3. Miniaturized worldwide UWB antennas are also introduced. Miniaturized worldwide UWB antennas that have compact sizes of (30x20x1.5) mm3, and (15x15x1.5) mm3 are also investigated. The designed worldwide UWB antennas cover the UWB spectrums defined by the electronic communication committee (ECC), 6--8.5 GHz, and the common worldwide UWB spectrum, 7.4--9 GHz. A system consisting of two identical antennas (transmitter and receiver) is built in the Antennas and Propagation Lab at Southern Illinois University Carbondale (SIUC) to test the coupling properties between every two identical antennas. The performance of that system is analyzed under different conditions to guarantee that the transmitted signal will be correctly recovered at the receiver end. The designed UWB antennas can be used in many short range applications such as wireless USB. Wireless USB is used in PCs, printers, scanners, laptops, MP3 players, hard disks and flash drives. A new technique is introduced to widen the impedance bandwidth of dielectric resonator antennas (DRAs). DRA features compactness, low losses, and wideband antennas. Different compact UWB DRAs are investigated in this dissertation. The designed DRAs cover a wide range of frequency bands such as, 6.17--24GHz, 4.23--13.51GHz, and 4.5--13.6GHz. The designed DRAs have compact sizes of 1x1x1.5cm 3, 0.9x0.9x1.32cm3, 0.6x0.6x1cm 3, and 0.6x0.6x0.9cm3; and cover the following frequency bands 4.22--13.51GHz, 4.5--13.6GHz, 6.1--23.75GHz, and 6.68--26.7GHz; respectively. The proposed DRAs may be used for applications in the X, Ku and K bands such as military radars and unmanned airborne vehicles (UAV). |
