baluneista

A balun is a device that converts between balanced and unbalanced electrical signals, most commonly used at radio frequencies to connect balanced antennas (such as dipoles or Yagis) to unbalanced feed lines (such as coaxial cables). By doing so, baluns help preserve the intended impedance of the antenna system and reduce unwanted currents on the outside of the feed line, which can cause stray radiation and interference.

There are two main families of baluns: transformer baluns and choke baluns. Transformer baluns provide an impedance transformation and may present ratios such as 1:1, 4:1, or 9:1, depending on the antenna and feed line. They are often built with windings on ferrite cores or as transmission-line transformers based on established winding geometries (for example, Ruthroff or Guanella designs). Choke baluns, also called current baluns, are intended to suppress common‑mode currents on the feed line without changing the differential impedance between the antenna terminals.

Common configurations include bifilar windings on a toroidal core, coaxial baluns where the coax is treated as a winding around a core to choke unwanted currents, and commercial adapters that integrate core materials and cables for ease of use. Practical use spans amateur radio, broadcast reception, and some telecom installations, wherever a balanced antenna needs to be fed with an unbalanced line.

Design considerations focus on the intended frequency range, the desired impedance transformation, power handling, core material, and mechanical construction. The performance of a balun is tied to these factors; broad-band designs require careful material selection and layout to minimize losses and ensure stable impedance across the operating band.