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Descripción
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| UWB systems are currently becoming more and more important, especially due to the need for high transmissions speeds. However, their range of application is not restricted to the communications field. They are also widely used in radar, collision detection systems in cars, and in medical imaging. In communications, the principal advantages of this technology over others are the robust characteristics it brings to multi-path environments and its low degree of interference with other systems, through the use of expanded spectrum techniques at low power. The systems performance and characteristics are heavily dependent on the design of the radiating element. The requirements placed on UWB antennas in terms of size, phase linearity and spectral efficiency are more demanding than for narrow band antennas. Traditional parameters, such as gain and reflection coefficient, are not sufficient to analyse their performance and characteristics. It is necessary to characterise them more fully from other points of view, by adding new figures of merit. The first part of this chapter presents the requirements, in generic terms, that are desirable in a UWB antenna. Apart from the typical demands on any radiating system in terms of matching and radiation pattern, other specifications must be guaranteed as due to the requirements of pulsed transmission. Special attention is paid to modelling the pulses used in UWB, which are degraded by the radiating system, thus limiting the communication¿s features and performance. A knowledge of the parameters used to describe these antennas, and how to apply them correctly, is essential for there to be any guarantee of success when designing them. The second part of the chapter therefore shows the figures of merit that allow different UWB antennas to be compared, and how they vary in the frequency, time and space domains. The chapter ends with brief considerations on electromagnetic simulation in the time domain. | |
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Internacional
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No |
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DOI
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Edición del Libro
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1 |
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Editorial del Libro
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Imperial College press |
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ISBN
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978-1-84816-491-8 |
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Serie
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Título del Libro
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Ultrawideband antennas - Design and applications |
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Desde página
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29 |
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Hasta página
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49 |