Current Tendencies and Some Unresolved Problems
Over a decade has passed since the United States Federal Communication Commission specified the frequency band for ultra wideband applications; since then this technology has become an area of study not only in the research community, but also for academic and industry sectors. In addition, like many other technological developments which were developed in military environments, UWB designs are now also available for civilian implementations. The importance of the subject is illustrated by the vast quantity and variety of books, journal papers, and conference presentations on the topic that can be found in the open literature. In the area of antennas, for instance, we can cite a number of books directly dedicated to the fundamentals and design of UWB radiators (e.g., [1-3]), as well as other texts that indirectly address aspects related to the UWB antenna principles .