February Fourier Talks 2008

Ultrawideband Definitions and Waveforms

The last decade has witnessed increased interest in ultrawideband electromagnetic systems, particularly in the areas of radar, communications, and high-power directed energy. Different groups within the engineering and scientific communities have preferred definitions of bandwidth and ultrawideband. Each group attempts to define a measure of the spectral widths of signals and systems and appropriate criteria to categorize them in a meaningful way. Unfortunately, existing definitions are not mutually consistent, since they are also influenced by the special needs and the understandably focused viewpoints of the respective communities. Defining UWB signals and systems unambiguously requires: (1) a definition of bandwidth; and (2) a categorization scheme in terms of bandwidth. This talk discusses issues associated with defining bandwidth and various spectral categorization schemes by considering several ideal waveforms (exponentially damped sine, Gaussian, half-cycle sine, linear-frequency-modulated sine, etc.). Furthermore, since much recent research has addressed the design and optimization of waveforms, conditions on waveforms that ensure physical relevance to real systems are also postulated.