Baluns

For related information on the subject, see also our articles on common mode interference and impedance matching.

Baluns

The balun is a device (often a transformer) that can:

• match a balanced antenna (dipole) to an unbalanced feedline (coax)

• match an unbalanced antenna (quarter-wave vertical) to a balanced feedline

• electrically isolate the feedline

• choke common-mode currents (caused by unbalanced antennas)

Although a balun can quench common-mode currents, it doesn't necessarily transform impedances.

Tuned Stub

Folded Balun

Pawsey Stub

Coax balun

Split coax balun