This thesis focuses on Ultra Wideband (UWB) antenna designs and analysis. Studies have been undertaken covering the areas of UWB fundamentals and antenna theory. UWB wireless technology is being considered as the solution to overcome data rate bottlenecks in the wireless communications and applications. UWB is able to achieve high data transmission rates because it transmits data over a very large spectrum of frequencies from 3.1 GHz to 10.6 GHz (7.5 GHz). Consequently, it provides many challenges for design in the communications arena, including antenna design.  The main objective of this thesis is to study, design, analyze and implement novel UWB low profile printed patch antennas that satisfy UWB technology requirements. Several techniques are used for optimal UWB bandwidth performance of the UWB antenna designs in this thesis. The undertaken thesis focuses on planar antennas printed on PCBs. Therefore, this research introduces novel five designs of microstrip-fed, small, low-profile, printed microstrip UWB antennas using different bandwidth-enhancement techniques to satisfy UWB bandwidth. According to their geometrical shapes, they can be classified into two types: the first types are stepped UWB antennas which are namely: a stepped-trapezoidal patch antenna and a trimmed notch-cut patch antenna. The second ones are beveled UWB antennas which are namely: an elliptical patch antenna, a double-beveled patch antenna, and a band-rejected elliptical patch antenna.  It has been demonstrated numerically and experimentally that the proposed antennas are suitable for UWB systems. They can provide satisfactory frequency domain performance, including ultra-wide bandwidth with nearly omni-directional radiation patterns, relatively flat gain and very good radiation efficiency. These features make them very suitable for UWB communications and applications, such as wireless personal area networks (WPANs) applications