Since the acceptance of unlicensed use of the Ultra-Wideband (UWB) technology in the range between 3.1 and 10.6 GHz in the USA (FCC, 2002) and more recently between 3.4 and 8.5 GHz in Europe (ETSI, 2008), the realization of low-cost UWB wireless systems is considered a fundamental research goal both for military and commercial applications. The possible use and benefits of UWB technology are significant and among its potential applications, high-resolution radar and short-range ultra-high speed data transmission are very attractive. In this scenario, design, fabrication and characterization of effective antennas for UWB systems are challenging tasks with respect to the case of narrowband systems. A suitable UWB antenna should be capable of operating over an ultra-wide bandwidth. Therefore it is necessary to guarantee a good behavior of the antenna in the band of interest in terms of impedance matching with the transmitter, radiation and time-domain properties. Moreover, recent UWB antenna development tends to focus on ultra-compact planar antennas as they are more practical in terms of manufacturing, integration with the system electronics board and form factor. Typical configurations exhibit radiation patterns similar to the traditional monopole/dipole antennas, i.e. they behave as omnidirectional radiators in the plane normal to the radiating element. This feature is desirable in UWB devices which do not have a fixed or a-priori defined orientation with respect to the environment and thus when it is not necessary to favour any specific direction. On the other hand, strongly directive radiators are required for radar applications, especially when low-power, lowinterference and high-resolution devices are needed. Directive UWB radiators are also interesting towards several complementary goals, e.g. to provide extra radio link gain to single antenna transceivers, to mitigate the effects of multipath in the indoor UWB channel, and, last but not least, to result in a high front-to-back ratio, which is desirable in many applications such as in wireless body-area networks (WBAN). In the past few years, several printed broadband monopole-like configurations have been reported for UWB applications, but presently, very few efforts have been made to increase their directionality. This chapter intends to provide the reader with two different design methodologies for increasing the directivity of planar UWB antennas. In section 2, a novel antenna layout will be presented, as the result of subsequent modifications of a native 1