This is a core type transformer in which the windings are wound on a non-magnetic strip. The magnetic flux linkages are made through air as corebetween the primary and secondary. The following image shows an air-core transformer.

Advantages

• The hysteresis and eddy current losses are low in these Air core transformers.
• Noise production is low.

Disadvantages

• The reluctance is high in Air core transformers.
• Mutual inductance is low in Air core compared to Iron-core transformers.

Applications

• Audio frequency transformers.
• High frequency radio transmissions.