Practical RF Handbook, 4th Edition

4

RF transformers

Introduction

RF transformers are used for two main purposes: to convert from one impedance level to another, or to provide electrical isolation between two circuits. Often, of course, isolation and impedance conversion are both required, and a suitable transformer fulfills both these functions with minimal power loss. Examples of transformers used mainly for isolation include those used to couple in and out of data networks and pulse transformers for SCR firing. Examples used mainly for impedance conversion include interstage transformers in MOSFET VHF power amplifiers and the matching transformer between a 50 Ω feeder and a 600 Ω HF antenna. Such a matching transformer may also be required to match an unbalanced feeder to ...