Book Review

## Microwave engineering books

There are a number of excellent textbooks on microwave engineering. Below are brief reviews of some of the microwave books I have read.

Introduction to Microwave Circuits: Radio Frequency and Design Applications by R. J. Weber (431 pages, 2001)
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This book contains extensive discussion of S-parameters, stability, filters, oscillators, amplifiers, and components. Useful appendices contain formulas for calculating microstrip impedances and measurement and modeling of components. Extensively uses matrix algebra and Smith charts. Although the treatment is mostly mathematical, the book also contains a number of circuit diagrams and graphs. Compared to Ishii's book (below), there are relatively few diagrams of the physical layout of the devices. In the last chapter, the author walks the reader through the design of a 1.25 GHz amplifier, oscillator, and filter. In this chapter the treatment of parasitics, which are extremely important at microwave frequencies, finally becomes clear. [Disclaimer: I have not finished reading this book.]

Microwave Engineering, 2nd ed. by T. K. Ishii (564 pages, 1989)

This is an excellent introductory book on microwave engineering. It begins with a detailed explanation of waveguides, treating microstrips as a special case. Although its emphasis is on theory, Ishii takes great pains to ensure that the reader also acquires an intuitive understanding of each topic. The treatment of microstrips, described in the chapter on solid-state MMIC waveguide components, is a particularly well-done example. The treatment is more concrete than Weber; for example, Weber mentions circulators only in the context of their S-parameters, while Ishii, in addition to describing their S-parameters, also describes how circulators actually work and what they're good for. There are also chapters on MMICs, microwave antennas, and impedance matching. Despite their importance, however, parasitics are barely mentioned. A brief discussion of noise measurement is hidden in the chapter on thermionic devices. Later chapters discuss power devices, including masers, klystrons, magnetrons, and traveling-wave tubes. Contains about equal numbers of diagrams and equations, along with many circuit diagrams.

The ARRL UHF/Microwave Experimenter's Manual by ARRL (446 pages, 2000)

This book, which consists of short articles by various authors, covers propagation, design techniques, antennas, and EME communications. Since it's written primarily for ham radio operators, it concentrates primarily on 144 and 432 MHz. The coverage is far more concrete than the other books, and discusses the various connectors, cables, components, and practical design techniques, including microstrips, for making oscillators, amplifiers, and transmission lines. Unlike the other books, this one has photos of the finished product; surprisingly, the authors use mostly discrete leaded components, which gives their finished devices an unnatural and amateurish appearance. Presumably, the rationale is that readers would have difficulty with surface mount construction. This, along with the absence of microchips, makes the book seem a bit old-fashioned. However, it contains a lot of useful introductory information, including a very good explanation of S-parameters, without bogging the reader down in math.

Planar Microwave Engineering: A Practical Guide to Theory, Measurements and Circuits by Thomas H. Lee (862 pages + CD, 2004)

If you consider the degree of rigor or "impedance" of a book as the ratio of the number of equations to the number of words, you will find that Planar Microwave Engineering has a much lower impedance than the textbooks by Ishii and Weber. Although all the important equations are there, the author's more folksy narrative style, not the presence of more information or detailed derivations, is the main reason why this book is so much bigger than its competitors. This approach has a solid rationale: to do their actual design, most engineers today would not calculate things by hand, but would use Microwave Office or AppCAD (which is included on the CD, along with LTSpice and some other very useful software). This book gives you the background you need to understand whether the results provided by the software actually make sense.

Throughout the book, the author also emphasizes the importance of making estimations of parameters such as reactance that may not be accounted for by the software. For example, he gives useful formulas for estimating the parasitic inductance of surface-mount components of different sizes. In fact, the role of parasitics is emphasized throughout the book. On some topics, though, the author's love of talking and his reluctance to make the material too technical gets in the way of providing a clear explanation. For example, even- and odd-mode excitation are explained much less clearly than in Günter Kompa's book on microstrips. The description of Smith charts is somewhat lacking in details. However, while the book glosses over some topics, it makes up for it by including hundreds of practical details derived from the author's vast experience that are not found elsewhere.

July 9, 2006 Back