Timed Arrays

PREFACE

Antenna arrays have been around for more than a century now. Decades after their introduction, beam steering using phase shifters heralded the introduction of phased arrays. Phased arrays with the help of advancements in computers and electronics morphed into the active electronically scanned array (AESA). As this book shows, a phased array has limited performance, because the design and analysis techniques used are based on phase which is a narrow band concept. High bandwidth signals in a dynamic environment place much higher demands on an antenna array.

This book is an introduction to timed arrays. Phased array is a well-established area with many books already written. Timed array is the next step in which wide bandwidth, large scan sectors, large apertures, and adaptive approaches require an analysis in the time domain rather than the traditional steady-state approach.

The first three chapters lay the foundation for the rest of the book. Arrays are presented from both the usual narrow band approach and from a modulated signal approach. Chapter 4 covers wideband elements and other element issues, such as mutual coupling. Chapter 5 describes feed networks, while Chapter 6 introduces active electronics. An important component of timed arrays is the time delay unit. Chapter 7 describes the need, technology, and placement in the feed network of time delay units. Finally, Chapter 8 introduces different types of adaptive and reconfigurable arrays.

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