Air Core Transformers: Know the Types and Benefits
Many small electronic devices such as radios use air core transformers that are based on antenna coils. These coils are commonly found in radio transmission systems. The reason they are widespread among communication devices is they lack a core, making them ideal for portable devices.
Here are some essential facts about air core transformers and how they are used:
What Air Core Transformers Do An air core transformer, which has a primary and secondary winding, operates on the principle of induction between a pair of magnetically linked coils or windings. Coils are typically wound on a non-magnetic surface like plastic while the cores are not made of iron or ferromagnetic materials, due to losses in hysteresis and eddy currents. Unlike conventional transformers, air core transformers generate flux through the windings.
Advantages of Air Core Transformers The key advantage to using an air core transformer is that the signal is neither distorted nor dissipated and does not generate noise. Other advantages are the lack of losses in hysteresis and eddy currents. Without a core, air core transformer has a lighter weight, making it useful for pocket devices and portable camping equipment.
Types of Air Core Transformers The two main types of air core transformers are cylindrical and toroidal. A cylindrical air core transformer gets its name from how copper wires are wound around a round structure. The hollow cylinder provides a passage way for flux. A toroidal air core transformer uses copper wires wound around a ring, typically made of tough plastic. The unique coil winding minimizes stray coupling effects, making it ideal for applications using high frequencies.
In cylindrical transformers, the primary copper winding can be protected with a guard winding, which also improves impedance matching. The performance can be improved by connecting the guard winding to antenna receivers. Another way to enhance performance is to connect a capacitor to the winding.
Conclusion One of the best transformer solutions for portable electronic devices is an air core transformer. It doesn't weigh as much as a conventional transformer, but still works like one, since it utilizes induction between two magnetically linked windings.