# The Book End

Ultra Wideband Signals and Systems in Communication Engineering

M. Ghavami, L.B. Michael and R. Kohno

John Wiley & Sons Ltd. • 275 pages; $90

This book focuses on the basic signal processing that underlies current and future ultra wideband (UWB) systems. The introduction offers a brief look at why UWB is considered to be such an exciting wireless technology for the near future. Chapter 1 presents the basic properties of UWB. The power spectral density, basic pulse shape and spectral shape of these pulses are examined. Chapter 2 examines in detail how to generate pulse waveforms for UWB systems for both simple cases, such as the Gaussian pulse shape, and more complex orthogonal pulses. Chapter 3 looks at different signal processing techniques for UWB systems. It begins with a review of basic signal processing techniques, including both frequency and time domain. The Laplace, Fourier and z-transform are reviewed and their application to UWB is discussed. The wireless indoor channel and how it should be modeled for UWB communications is considered in Chapter 4. Chapter 5 takes a look at some of the fundamental communication concepts and how they should be applied to UWB. A basic communication system consisting of transmitter, receiver and channel is discussed. Chapter 6 is concerned with ultra wideband antennas and arrays of antennas. This is considered one of the most difficult problems that must be overcome before the widespread commercialization of UWB devices takes place. Positioning and location using both traditional techniques and UWB is discussed in Chapter 7. The advantages of UWB, particularly the extremely precise positioning that is theoretically possible, are examined. Chapter 8 concludes the book with a brief look at some current applications that use UWB technology as well as an overview of current chipsets and possible future UWB products.

To order this book, contact:

John Wiley & Sons Ltd.

The Atrium, Southern Gate Chichester, West Sussex,

PO19 8SQ, England

+44 1243 779777

Lumped Element Quadrature Hybrids

David Andrews

Artech House • 225 pages; $119, £70

Quadrature hybrids find wide applications in radio frequency (RF) and microwave circuits and systems. In answer to this need, considerable attention has been paid to distributed circuits with quadrature properties, particularly for microwave applications. RF engineers too find quadrature hybrids useful, although they prefer lumped element circuits for reasons of size. Microwave engineers will be surprised by the breadth of applications for lumped element quadrature hybrids, which offer the prospects of reduction in circuit size, ease of fabrication and remarkable performance. RF engineers will also find useful the material presented. This book is structured in a similar manner to the treatment of filter theory because the subjects have much in common. Chapter 1 gives an overview of the various forms of quadrature hybrids and their applications, and then shows a method for assessing the relative performance of a particular design. Chapter 2 examines the constraints that theory places on quadrature hybrid circuits, and more particularly, lumped element forms. Chapter 3 is a treatment of the subject of approximation, a concept familiar to the filter designer. Quadrature hybrids are also filter circuits and their performance is one of optimization rather than perfection. Chapter 4 deals with the subject of circuit synthesis and shows how the various approximation functions can be given their expression in electrical networks. Chapter 5, titled “Practical Design,” might also be titled “Realizations” and shows how the theoretical circuits can be made in practice. A number of concept circuits are described, illustrating most of the aspects described in the theoretical chapters. The final chapter, “Special Topics,” shows how the theory and application of quadrature hybrids can be extended to related matters, which are of themselves also useful.

To order this book, contact:

Artech House

685 Canton St.

Norwood, MA 02062

(781) 769-9750 ext. 4030;

or 46 Gillingham St.

London SW1V 1HH, UK

+44 (0) 207-8750