Air Core Inductors

Inductance

Current

• Air core — flat to the thermal limit
• Ferrite core — saturates

• Inductance holds from zero current to the thermal limit. There is no core, so there is nothing to saturate and nothing to move with temperature.
• No core loss either, so Q stays high at frequency where a ferrite of the same value would be heating.
• The cost is permeability. An air core needs far more turns for the same inductance, so it is physically larger — which is why it is specified where linearity matters more than size.