The aim of this book is to provide interesting material to (graduate) students and researchers working in the field of commercial Ultra Wide Band (UWB) wireless communications. The book will also be useful for the practicing engineers from industry who deal with the wireless systems that are designed and analyzed with the UWB technique. UWB technology has a history dating back one hundred years when G. Marconi sent the first ever wireless transmission from the Isle of Wight to Cornwall on the British mainland using spark-gap transmitters. In the past three decades military developed the UWB technology for ground penetrating radar. Ultra wide band communication is based on the transmission of very short pulses with relatively low energy. In the near future this technology may see increased use for high-speed short range wireless communications and ranging.