Balun

Balun (from the English balun - balanced-unbalanced) is a slang term for balancing devices that convert an electrical signal from balanced to unbalanced and vice versa. Most often, different types of winding transformers made on magnetic cores are used for this, but this is not always true - sometimes a balancing device can be implemented as quarter-wave short-circuited segments made of coaxial cable segments.

Structurally, it can be done in different ways, most often on an annular (less often open) ferrite magnetic core .

They are widely used in radio engineering for matching heterogeneous communication lines; antennas with communication lines; output and input stages of communication equipment with antenna-feeder path.

Sometimes "balun" also refers to devices designed to increase the inductance of the braid and thereby reduce the "leakage" of high-frequency currents that occur when the central core leaves the braid on the outside of the braid. For this, they can, for example, simply push ferromagnetic rings close to each other on the cable close to the antenna, or, if the cable is thin enough, make several coils with such cable around the ferrite girth.