TABLE OF CONTENTS This chapter is a digest of important investigative results observed during experimentation by the author. Significant points concerning the capabilities of ferrite-core transformers are also reviewed. Some of the comments are contrary to conventional wisdom on the subject. It is hoped that the information presented in this book will assist the circuit designer and the analyst, and stimulate additional research in the field.
Some of the more important additions in this second edition are: (A) an in-depth study of Guanella's approach to transmission line transformers, (B) a comparison between the approaches of Guanella and Ruthroff, (C) a new look at balun transformers, (D) parallel transformers, (E) broadband, dual-ratio transformers, (F) fractional-ratio balun transformers and (G) many more practical transformer designs.
Since the publication of the first edition, analytical and experimental results (by the author) on a great variety of transformers revealed some interesting comparisons of the approaches by Guanella (ref 1) [1] and Ruthroff (ref 9) to transmission line transformer theory and applications. Their papers are considered the cornerstones of this class of transformers. Guanelia was concerned with the matching of the push-pull output of a 100-W vacuum-tube amplifier to coaxial cable in the 100- to 200-MHz range. Ruthroff's research, on the other hand, was mainly concerned with broadband matching at low signal levels to coaxial cable, radio, millimeter waveguide and early optical fibers (for the emerging digital techniques). Many of his transformers performed into the gigahertz range and handled nanosecond pulses. Besides the power...
