Air winding transformers are used for transporting radio-frequency currents. The transformers primary coil, the winding is linked with windings through air, the use of air makes the transformer light and noise free.
The two main types of air winding transformers are cylindrical and toroidal. A cylindrical air transformer contains copper wires that are wound around a round structure. With the hollow cylinder providing a passage way for flux. The other type a toroidal air transformer uses copper wires wound around a ring, often made of tough plastic. The unique coil winding minimizes stray coupling effects, making it ideal for applications using high frequencies.