Electronically Scanned Arrays

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Electronically Scanned Arrays
Copyright © 2007 by Morgan & Claypool All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means—electronic, mechanical, photocopy, recording, or any other except for brief quotations in printed reviews, without the prior permission of the publisher. Electronically Scanned Arrays Robert J. Mailloux
Electronically Scanned Arrays
Robert J. Mailloux
University of Massachusetts, Amherst, MA
SYNTHESIS LECTURES ON ANTENNA;Claypool
Publishers
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ABSTRACT
Scanning arrays present the radar or communications engineer with the ultimate in antenna flexibility. They also present a multitude of new opportunities and new challenges that need to be addressed. In order to describe the needs for scanned array development, this book begins with a brief discussion of the history that led to present array antennas. This text is a compact but comprehensive treatment of the scanned array, from the underlying basis for array pattern behavior to the engineering choices leading to successful design. The book describes the scanned array in terms of radiation from apertures and wire antennas and introduces the effects resulting directly from scanning, including beam broadening, impedance mismatch and gain reduction and pattern squint and those effects of array periodicity including grating and quantization lobes and array blindness. The text also presents the engineering tools for improving pattern control and array efficiency including lattice selection, subarrray technology and pattern synthesis. Equations and figurers quantify the phenomena being described and provide the reader with the tools to tradeoff various performance features. The discussions proceed beyond the introductory material and to the state of the art in modern array design.
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Contents
1. Basic Principles and Applications of Array Antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 A Historical Perspective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.3 Antenna and Array Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.3.1 Array Scanning: Linear Array . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 1.3.2 Array Pattern Shape and Beamwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 1.3.3 Array Pattern ‘Squint’ and Bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 1.3.4 Grating Lobes of Linear Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 1.3.5 Grating Lobes of Planar Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 1.3.6 Array Directivity Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 1.4 Multiple Beam Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Element Coupling Effects in Array Antennas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27 2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 2.1.1 Array Element Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 2.1.2 Array Element Patterns for Single and Multi-mode Elements . . . . . . . . 29 2.2 Radiation of Wire and Aperture Antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 2.2.1 The Radiation of a Single Wire or Aperture . . . . . . . . . . . . . . . . . . . . . . . . 30 2.2.2 Radiation from a Dipole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 2.2.3 Radiation from a Dipole in an Array of Terminated Dipoles . . . . . . . . . 35 2.3 Array Element Patterns in an Infinite Array. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37 2.4 Finite Arrays and Wide-Band Arrays. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42 Array Pattern Synthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 3.2 Synthesis Techniques for Sector Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 3.2.1 The Fourier Synthesis Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 3.2.2 The Woodward Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 3.3 Synthesis of Pencil Beam Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 3.3.1 Taylor Line Source Synthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 3.3.2 Bayliss Line Source Synthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 3.4.1 The Alternating Projection Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54