Symetrizační člen SA IV-V

A typical antenna has a balanced output of 300 Ohm impedance ratio, while a coaxial cable is an imbalanced load of 75 Ohm impedance. This is why an indirect connection must be created to fit an antenna with a coaxial cable: an impedance transformer must be used. An impedance transformer is a passive device which uses a transformer to change the impedance, and switch between balanced and imbalanced load. Usually, the transformer is of standard construction, with ferrite core. Sometimes transformers are optimized for working in a particular band, e.g. C0001 for channels 1-12, while impedance transformers working on channels 21-69 are mostly printed ones.