The first two editions of Secrets of RF Circuit Design were met with a tremendous and heartwarming response; the sales of those books were more than satisfying especially because the mail was so positive. Because of the positive responses to the first two editions, the publisher and I decided to make this third edition available.

In this third edition, I ve incorporated a lot of the feedback from readers, received both in person and by mail. For example, the coverage of direct-conversion receivers (always a popular construction project) has been greatly expanded. In addition, chapters on Very Low Frequency (VLF) have been added for the benefit of Lowfers and their kin. I also added a chapter on designing and building inductance-capacitance (LC) RF filters (high-pass, low-pass, bandpass, and notch). These filters not only make projects work better, but they also keep electromagnetic interference at bay. Another feature is coverage of double-balanced mixers. These devices are now more accessible, in both integrated circuit and diode versions, and are a step ahead of the other forms of mixer circuits.

During the 20 or more years that I have written articles for electronics and amateur radio magazines, such as Popular Electronics, Radio Electronics, Popular Communications, Nuts n Volts, and Ham Radio, it has become apparent that many professional and amateur electronics people consider radio-frequency (RF) electronics as something of a hard-to-do, deep mystery.

Perhaps the major contributor to this attitude is that formulas and circuits don t seem to work on the bench...