A periodic surface is an assembly of identical elements arranged in a one or two-dimensional array. Such surfaces have various effects on incident electromagnetic waves. Their applications range from antennas to stealth aircraft.This book discusses finite antenna arrays and how to minimize the radar cross section of these arrays. "Ben has been the world-wide guru of this technology...Ben Munk has written a book that represents the epitomy of practical understanding." W. Bahret, United States Air Force Frequency selective surfaces (FSSs) have important military and civilian applications including antenna theory, satellite communications and stealth technology Author is an authory on the subject, having been instrumental in the development of stealth technology for the US Air Force Much of the material in this book was deemed classified due to its importance to defence

Why did I write this book? The approach to engineering design has changed considerably over the last decades. Earlier, it was of utmost importance to first gain insight into the physics of the problem. You would then try to express the problem in mathematical form. The beauty here was, of course, that it then often was quite simple to determine the location of the extreme values such as the maxima and minima as well as nulls and asymptotic behavior. You would then, in many cases, be able to observe which parameters were pertinent to your problem and in particular which were not. It was then followed by actual calculations and eventually by a meaningful parametric study that took into account what was already observed earlier. The problem with this approach was, of course, that it required engineers and scientists with considerable insight and extensive training (I deliberately did not say experience, although it helps). However, not everyone that started down this road would finish and not without a liberal dose of humiliation. It is therefore quite understandable that when the purely numerical approaches appeared on the scene, they soon became quite popular. Most importantly, only a minimum of physical insight was required (or so it was thought). The computers would be so fast that they would be able to calculate all the pertinent cases. These would then be sorted out by using a more or less sophisticated optimization scheme, and the results would be presented on a silver platter completely untouched by the human mind. It would be incorrect to state that the numerical approach has failed. It has in many cases produced remarkable results. However, the author is keenly aware of several cases that have been the subject of intense investigation for years and still have not produced a satisfactory solution, although some do exist—most often xxi xxii PREFACE because the computer has been directed to incorporate all kinds of parameters that are alien to this particular problem. Or lack of physical insight has prevented the operator from obtaining a meaningful parametric study—for example, in cases where a solution does not exist in the parametric space considered. The author has watched this development with considerable concern for several years. One of his colleagues stated recently that a numerical solution to a somewhat complex problem of his could only be used to check out specific designs. An actual optimization was not possible because of the excessive computer time involved. That almost sounds like an echo of other similar statements coming from the numerical camp. A partial remedy for this calamity would be, of course, to give the students a better physical understanding. However, a fundamental problem here is that many professors today are themselves lacking in that discipline. The emphasis in the education of the younger generation is simply to write a computer program, run it, and call themselves engineers! The result is that many educators and students today simply are unaware of the most basic fundamentals in electromagnetics. Many of these shortcomings have been exposed at the end of each chapter of this book, in a section titled “Common Misconceptions.” Others are so blatantly naive that I am embarrassed to even discuss them. What is particularly disturbing is the fact that many pursue these erroneous ideas and tales for no other reason than when “all the others do it, it must be OK!” Neither this book nor my earlier one, Frequency Selective Surfaces, Theory and Design, make any claims to having the answers to all problems. However, there are strong signals from the readers out there that they more and more appreciate the analytic approach based on physical understanding followed up by a mathematical analysis. It is hoped that this second book will be appreciated as well. The author shared this preface with some of his friends in the computational camp. All basically agreed with his philosophy, although one of them found the language a bit harsh! However, another informed him before reading this preface that design by optimization has lately taken a back seat as far as he was concerned. Today, he said, there is a trend toward understanding the underlying mathematics and physics of the problem. Welcome to the camp of real engineering. As they say, “there is greater joy in Heaven over one sinner who makes penance than over ninety-nine just ones.” Columbus, Ohio BEN MUNK Acknowledgments As in my first book, Frequency Selective Surfaces, Theory and Design, three of my many mentors stand out: Mr. William Bahret, Professor Leon Peters, Jr., and Professor Robert Kouyoumjian. They were always ready with consultation and advice. That will not be forgotten. Further support and interest in my work was shown by Dr. Brian Kent, Dr. Stephen Schneider, and Mr. Ed Utt from the U.S. Air Force. After completion of the development of the Periodic Method of Moments, the PMM code, the Hybrid radome, low RCS antennas, and more, the funding from the Air Force shifted into more hardware-oriented programs. Fortunately, the U.S. Navy needed our help in designing very broadbanded bandstop panels. Ultimately, this work resulted in the discovery of surface waves unique to finite periodic structures, which are treated in great detail in this book. The help and advice from Mr. Jim Logan, Dr. John Meloling, and Dr. John Rockway is deeply appreciated. However, the most discussed subject was the Broadband Array Concept. It was set in motion by two of the author’s oldest friends, namely Mr. William Croswell and Mr. Robert Taylor from the Harris Corporation. This relationship resulted in many innovative ideas as well as support. So did my cooperation with Mission Research (home of many of the author’s old students). My deep-felt thanks goes to all who participated in particular Errol English who wrote Section 9.6 about Tapered Periodic Surfaces, and Peter Munk who supplied Section 3.7 investigating Periodic Surfaces with arbitrary oriented elements. My good friend and mentor, Professor John Kraus, once stated that students really are at the university to “straighten” the professors out, not the other way around. I whole-heartedly agree. In fact, had it not been for my last two students, Dr. Dan Janning and Jonothan Pryor, this book would not have been written. I am particularly indebted to Jonothan, who tirelessly ran computer programs and xxiii xxiv ACKNOWLEDGMENTS curves for numerous cases in this book. He is currently interviewing. Lucky is the company that “secures” him. Deep-felt thanks also go to my many friends and colleagues at the OSU ElectroScience Lab who supported me—in particular to Prof. Robert Garbacz, who graciously reviewed Chapter 2 concerning the RCS of antennas. Finally, I was very lucky to secure my old editorial team, namely, Mrs. Ann Dominek, who did the typing, and Mr. Jim Gibson, who did a great deal of the drawings. In spite of their leaving the laboratory, they both agreed to help me out. And a fine job they did. Thank you. BEN MUNK

"...Ben has been the world-wide guru of this technology, providing support to applications of all types. His genius lies in handling the extremely complex mathematics, while at the same time seeing the practical matters involved in applying the results. As this book clearly shows, Ben is able to relate to novices interested in using frequency selective surfaces and to explain technical details in an understandable way, liberally spiced with his special brand of humor... Ben Munk has written a book that represents the epitome of practical understanding of Frequency Selective Surfaces. He deserves all honors that might befall him for this achievement." -William F. Bahret. Mr. W. Bahret was with the United States Air Force but is now retired. From the early 50s he sponsored numerous projects concerning Radar Cross Section of airborne platforms in particular antennas and absorbers. Under his leadership grew many of the concepts used extensively today, as for example the metallic radome. In fact, he is by many considered to be the father of stealth technology. "This book compiles under one cover most of Munk's research over the past three decades. It is woven with the physical insight that he has gained and further developed as his career has grown. Ben uses mathematics to whatever extent is needed, and only as needed. This material is written so that it should be useful to engineers with a background in electromagnetics. I strongly recommend this book to any engineer with any interest in phased arrays and/or frequency selective surfaces. The physical insight that may be gained from this book will enhance their ability to treat additional array problems of their own." -Leon Peters, Jr. Professor Leon Peters, Jr., was a professor at the Ohio State University but is now retired. From the early sixties he worked on, among many other things, RCS problems involving antennas and absorbers. This book presents the complete derivation of the Periodic Method of Moments, which enables the reader to calculate quickly and efficiently the transmission and reflection properties of multi-layered Frequency Selective Surfaces comprised of either wire and/or slot elements of arbitrary shape and located in a stratified medium. However, it also gives the reader the tools to analyze multi-layered FSS's leading to specific designs of the very important Hybrid Radome, which is characterized by constant band width with angle of incidence and polarization. Further, it investigates in great detail bandstop filters with large as well as narrow bandwidth (dichroic surfaces). It also discusses for the first time, lossy elements used in producing Circuit Analog absorbers. Finally, the last chapter deals with power breakdown of FSS's when exposed to pulsed signals with high peak power. The approach followed by most other presentations simply consists of expanding the fields around the FSS, matching the boundary conditions and writing a computer program. While this enables the user to obtain calculated results, it gives very little physical insight and no help in how to design actual multi-layered FSS's. In contrast, the approach used in this title analyzes all curves of desired shapes. In particular, it discusses in great detail how to produce radomes made of FSS's located in a stratified medium (Hybrid Radomes), with constant band width for all angles of incidence and polarizations. Numerous examples are given of great practical interest. More specifically, Chapter 7 deals with the theory and design of bandpass radomes with constant bandwidth and flat tops. Examples are given for mono-, bi- and tri-planar designs. Chapter 8 deals with bandstop filters with broad as well as narrow bandwidth. Chapter 9 deals with multi-layered FSS of lossy elements, namely the so-called Circuit Analog Absorbers, designed to yield outstanding absorption with more than a decade of bandwidth. Features material previously labeled as classified by the United States Air Force.

The Most Complete, Up-to-Date Coverage of the Finite Element Analysis and Modeling of Antennas and Arrays Aimed at researchers as well as practical engineers—and packed with over 200 illustrations including twenty-two color plates—Finite Element Analysis of Antennas and Arrays presents: Time- and frequency-domain formulations and mesh truncation techniques Antenna source modeling and parameter calculation Modeling of complex materials and fine geometrical details Analysis and modeling of narrowband and broadband antennas Analysis and modeling of infinite and finite phased-array antennas Analysis and modeling of antenna and platform interactions Recognizing the strengths of other numerical methods, this book goes beyond the finite element method and covers hybrid techniques that combine the finite element method with the finite difference time-domain method, the method of moments, and the high-frequency asymptotic methods to efficiently deal with a variety of complex antenna problems. Complemented with numerous examples, this cutting-edge resource fully demonstrates the power and capabilities of the finite element analysis and its many practical applications.

A Convincing and Controversial Alternative Explanation of Metamaterials with a Negative Index of Refraction In a book that will generate both support and controversy, one of the world's foremost authorities on periodic structures addresses several of the current fashions in antenna design—most specifically, the popular subject of double negative metamaterials. Professor Munk provides a comprehensive theoretical electromagnetic investigation of the issues and concludes that many of the phenomena claimed by researchers may be impossible. While denying the existence of negative refraction, the author provides convincing alternative explanations for some of the experimental examples in the literature. Although the debate on this subject is just beginning, Professor Munk has received support by various numerical simulations, winning him the encouragement of numerous experts in the field. The issues that are raised here have not been addressed thoroughly by the metamaterials community, and this book will serve as a catalyst for much healthy debate and discussion. Metamaterials: Critique and Alternatives is destined to become a classic resource for graduate students and researchers in electromagnetics, antenna theory, materials research, and chemistry.

This book teaches the finite-difference frequency-domain (FDFD) method from the simplest concepts to advanced three-dimensional simulations. It uses plain language and high-quality graphics to help the complete beginner grasp all the concepts quickly and visually. This single resource includes everything needed to simulate a wide variety of different electromagnetic and photonic devices. The book is filled with helpful guidance and computational wisdom that will help the reader easily simulate their own devices and more easily learn and implement other methods in computational electromagnetics. Special techniques in MATLAB® are presented that will allow the reader to write their own FDFD programs. Key concepts in electromagnetics are reviewed so the reader can fully understand the calculations happening in FDFD. A powerful method for implementing the finite-difference method is taught that will enable the reader to solve entirely new differential equations and sets of differential equations in mere minutes. Separate chapters are included that describe how Maxwell’s equations are approximated using finite-differences and how outgoing waves can be absorbed using a perfectly matched layer absorbing boundary. With this background, a chapter describes how to calculate guided modes in waveguides and transmission lines. The effective index method is taught as way to model many three-dimensional devices in just two-dimensions. Another chapter describes how to calculate photonic band diagrams and isofrequency contours to quickly estimate the properties of periodic structures like photonic crystals. Next, a chapter presents how to analyze diffraction gratings and calculate the power coupled into each diffraction order. This book shows that many devices can be simulated in the context of a diffraction grating including guided-mode resonance filters, photonic crystals, polarizers, metamaterials, frequency selective surfaces, and metasurfaces. Plane wave sources, Gaussian beam sources, and guided-mode sources are all described in detail, allowing devices to be simulated in multiple ways. An optical integrated circuit is simulated using the effective index method to build a two-dimensional model of the 3D device and then launch a guided-mode source into the circuit. A chapter is included to describe how the code can be modified to easily perform parameter sweeps, such as plotting reflection and transmission as a function of frequency, wavelength, angle of incidence, or a dimension of the device. The last chapter is advanced and teaches FDFD for three-dimensional devices composed of anisotropic materials. It includes simulations of a crossed grating, a doubly-periodic guided-mode resonance filter, a frequency selective surface, and an invisibility cloak. The chapter also includes a parameter retrieval from a left-handed metamaterial. The book includes all the MATLAB codes and detailed explanations of all programs. This will allow the reader to easily modify the codes to simulate their own ideas and devices. The author has created a website where the MATLAB codes can be downloaded, errata can be seen, and other learning resources can be accessed. This is an ideal book for both an undergraduate elective course as well as a graduate course in computational electromagnetics because it covers the background material so well and includes examples of many different types of devices that will be of interest to a very wide audience.

This is the first comprehensive treatment of conformal antenna arrays from an engineering perspective. While providing a thorough foundation in theory, the authors of this publication provide a wealth of hands-on instruction for practical analysis and design of conformal antenna arrays. Thus, you get the knowledge you need, alongside the practical know-how to design antennas that are integrated into such structures aircrafts or skyscrapers.

Based on the author's extensive research at MIT Lincoln Laboratory, this authoritative resource offers an in-depth description of adaptive array design, emphasizing the RF characteristics, mutual coupling among elements, and field testing methods. It provides you with proven techniques for challenging projects involving radar, communication systems and antenna design. For the first time in any book, you find design guidance on specialized types of arrays, using monopole radiating elements, slotted cylinders and ultrawideband dipoles. Moreover, this unique book presents a focused near-field technique that quantifies the far-field performance of large aperture radar systems and communication systems. The book presents example prototype phased array antennas, including discussions on monopole phased arrays, finite and infinite array analyses, measurements for planar arrays of monopole elements. Further, you get a detailed explanation of focused near-field polarization characteristics of monopole arrays as related to adaptive array testing in the near field. From the fundamentals of adaptive antennas and degrees of freedom for multiple beam antennas and phased arrays… to a test bed monopole phased array and the planar near field testing technique… to arrays of horizontally polarized loop-fed slotted cylinder antennas and ultrawideband dipole arrays, this comprehensive book offers you invaluable, hands-on knowledge for your work in the field.

Written by a leading expert in the field, this practical new resource presents the fundamentals of electromagnetics and antenna technology. This book covers the design, electromagnetic simulation, fabrication, and measurements for various types of antennas, including impedance matching techniques and beamforming for ultrawideband dipoles, monopoles, loops, vector sensors for direction finding, HF curtain arrays, 3D printed nonplanar patch antenna arrays, waveguides for portable radar, reflector antennas, and other antennas. It explores the essentials of phased array antennas and includes detailed derivations of important field equations, and a detailed formulation of the method of moments. This resource exhibits essential derivations of equations, providing readers with a strong foundation of the underpinnings of electromagnetics and antennas. It includes a complete chapter on the details of antenna and electromagnetic test and measurement. This book explores details on 3D printed non-planar circular patch array antenna technology and the design and analysis of a planar array-fed axisymmetric gregorian reflector. The lumped-element impedance matched antennas are examined and include a look at an analytic impedance matching solution with a parallel LC network. This book provides key insight into many aspects of antenna technology that have broad applications in radar and communications.

Electromagnetic materials have both civilian and defence applications, such as novel antenna designs and protection against high power transients in densely packed printed circuits. For certain applications, the materials may be required to have special frequency response or polarization response to meet the component or system specifications. An in-depth understanding of the responses of materials to electromagnetic waves may even enable us to design and fabricate materials with properties not found in nature.This book constitutes the proceedings of the Symposium on Electromagnetic Materials, which provided a forum for scientists and engineers to report the latest research findings, to exchange ideas and information, and to establish research links.