Balun Applications

BALUN is a word derived from terms applied to BALanced to UNbalanced transmission lines, and generally refers to an impedance matching device for interfacing two lines having different characteristic impedance and often one balanced line to one unbalanced line. (There are devices called UNUN’s, they are unbalanced to unbalanced devices.)

The balanced lines normally refer to twisted pair cables and the unbalanced lines to coaxial cables due to the way the cables are designed. The balun device generally consists of a radio frequency transformer having two windings matching the respective impedance of the lines. Often tuned to provide optimum matching, maximum return loss, minimum insertion loss and other frequency characteristics. Fitted with some type of connecting terminals for the balanced twisted pair end and a coaxial connector at the unbalanced coaxial end. Sometimes they also include voltage surge suppression components.