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Báo cáo hóa học: Department of Electrical Engineering, University of

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Department of Electrical Engineering, University of | EURASIP Journal on Applied Signal Processing 2005 3 252-272 2005 Hindawi Publishing Corporation Ultra-Wideband Radio Robert A. Scholtz Department of Electrical Engineering University of Southern California Los Angeles CA 90089 USA Email scholtz@usc.edu David M. Pozar Department of Electrical and Computer Engineering University of Massachusetts Amherst MA 01003 USA Email pozar@ecs.umass.edu Won Namgoong Department of Electrical Engineering University of Southern California Los Angeles CA 90089 USA Email namgoong@usc.edu Received 12 May 2004 The application of ultra-wideband UWB technology to low-cost short-range communications presents unique challenges to the communications engineer. The impact of the US FCC s regulations and the characteristics of the low-power UWB propagation channels are explored and their effects on UWB hardware design are illustrated. This tutorial introduction includes references to more detailed explorations of the subject. Keywords and phrases UWB radio UWB propagation UWB antennas UWB radio architectures selective RAKE receivers transmitted-reference receivers. 1. ORIGINS It has been said that paradigm shifts in design and operation of systems are necessary to achieve orders-of-magnitude changes in performance. It would seem that such events have occurred in the world of radio communications with the advent of ultra-wideband UWB radio. Indeed several remarkable innovations have taken place in the brief history of UWB radio. Initially transient analysis and timedomain measurements in microwave networks 1960s and the patenting of short-pulse often called impulse or carrierless or baseband or UWB radio systems in the early 1970s were major departures from the then-current engineering practices. For detailed descriptions of the early work in this field see 1 . Marconi s view of using modulated sinusoidal carriers and high-Q filters for channelization has so dominated design and regulation of RF systems since the early twentieth century that .