Ultrawideband Filter Technologies

Following the adoption by the Federal Communications Committee (FCC) in February 2002 [1] of the unlicensed use of ultrawideband (UWB) communications spectrum from 3.1 GHz to 10.6 GHz, there has been increasingly interesting research on UWB techniques by academics and private industry. UWB systems have several advantages: They have a bandwidth of 7.5 GHz, which can support a high transmission data rate (up to 500 Mb/s); they have low energy density over a wideband spectrum generated by short pulse excitation, which not only makes the UWB system difficult to intercept but also minimizes interference by other radio systems; and they have extremely low transmission energy (less than 1.0 mW), which is favorable for hand-held radio systems. UWB techniques have been used for many applications, such as positioning, rescue radar system for rescuing survivors buried under collapsed buildings in many emergency situations, imaging, short-range high-data-rate communication systems, and wireless personal area networks (WPANs) for personal computer and electronic devices.