In concluding this landmark eight-part design series on transistor amplifiers, hopefully some readers have taken to their benches to apply the tips offered by Dr. White. Those looking forward to more of this practical treatment can find it in his new book, *High Frequency Techniques: An Introduction to RF and Microwave Engineering*. The amplifier chapter of this 502-page text has served as the source for our eight-part article series on amplifiers, yet it is just one of ten chapters. The book covers the operating principles and design of antennas, directional couplers, and a wide range of filters. It is also an easily read presentation of practical fundamentals, including AC analysis, RLC networks, and distributed circuits. For example, it shows how to use Q to design an LC circuit to match any load to any source with just back-of-the-envelope calculations.

A full chapter is devoted to the Smith Chart, the invaluable tool for designing transmission-line circuits. As he notes, the key to understanding the Smith Chart is to "recognize that, although impedance varies in a complex manner as one moves away from the load on a lossless transmission line, reflection coefficient variation is quite simple, only its angle changes, not its magnitude!" With this principle, he constructs the Smith Chart and uses it to plot normalized impedance and admittance, reflection coefficient, and Q circles. The Chart is then used to design networks to match complex loads, to broadband them and find lumped equivalent circuits for distributed line lengths.

Dr. White covers electromagnetic (EM) field theory in an unassuming manner, presenting the reader with the necessary vector mathematics along the way as he does a laudable job of showing how to visualize Maxwell's four equations, essential relationships to the understanding of EM theory. This chapter, spanning more than 120 pages, starts with the basics of fields, such as the Earth's gravitational field, and continues through the laws of physics to Gauss's Law, Ampere's Law, and Faraday's Law of Induction—the basis of Maxwell's equations. The EM-chapter is extended in a natural transition to antennas and antenna patterns, presenting monopoles, dipoles, aperture antennas, and phased arrays. Waveguide fields are developed along with a novel method of defining absolute waveguide impedance using Green's functions. The chapter concludes by demonstrating the use of EM simulation software for transmission-line modeling.

The book has a generous collection of practical exercises at the ends of chapters to promote the reader's understanding of its wide range of subjects. Handy appendices are included that cover important equations, a review of complex number math, engineering symbols, material properties, standard waveguides and even a resistance chart for copper wire sizes. For any engineer working on RF/microwave issues, *High Frequency Techniques: An Introduction to RF and Microwave Engineering* by Joseph F. White, John Wiley & Sons, 2004 is a practical text that will be referred to again and again. (2004, 502 pp., hardcover, ISBN: 0-471-455911, $94.95. John Wiley & Sons, Inc., 111 River St., Hoboken, NJ 07030; (201) 748-6395, e-mail: [email protected], Internet: www.wiley.com.)