Despite previous books on UWB systems for radar systems and more recently, communications, no book exists that deals with the antennas and propagation of UWB for both communication and radar systems. This text provides up-to-date material on fundamental design concepts and principles for UWB antennas and arrays. In addition, the propagation of UWB radiation is addressed and gives a better understanding of the nature of propagation of UWB waves including interference, coexistence, diversity and MIMO (multiple-input, multiple output - transmission of the same information by multiple transmitters and multiple receivers) and propagation through biological materials. Existing and proposed applications of UWB technology is also looked at.