Symmetrizer (balun) - definition
Symmetrizer (balun) - definition
The symmetrizer, also known as balun (short for balanced-unbalanced), is an electronic device used to transform signals between symmetrical and asymmetrical lines. Its purpose is to ensure correct impedance matching and to minimise unwanted signal interference resulting from differences in the structure of the transmission paths.
In a symmetrical line, such as twisted-pair or symmetrical dipole, the signal is transmitted via two cables with equal parameters with respect to earth, which ensures high resistance to electromagnetic interference. In contrast, an asymmetrical line, such as a coaxial cable, transmits the signal via a single wire relative to a common ground. Without a suitable transformation, potential differences can arise when such lines are connected, leading to noise emissions, signal losses or common ground currents.
Baluns can be implemented in a variety of ways, depending on frequency and signal characteristics: as electromagnetic transformers, capacitive systems, or hybrid designs based on cores Ferrite Cores. In radiocommunication, television, radar systems and RFID technologies symmetisers play a key role in ensuring high quality signal transmission by eliminating asymmetry and suppressing interference from external sources.
In the context of antenna design, baluns are an indispensable design element, which enables proper adaptation between symmetrical antennas and asymmetrical transceiver systems, directly influencing radiation efficiency, impedance matching and limiting the emission of unwanted waves in the transmission path. A properly selected symmetriser not only improves the performance of an RF system, but also significantly affects its reliability and compliance with electromagnetic compatibility (EMC) standards.
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