Apparatus for an aerosol generating device

A method of determining a property of a susceptor arrangement for an aerosol generating device, wherein the susceptor arrangement is for heating an aerosol generating material, the method being performed by a controller of an aerosol generating device comprising the controller and a circuit comprising an inductive element for heating the susceptor, wherein the method comprises:

• determining, by the controller, a change in an electrical parameter of the circuit when the circuit is changed between an unloaded state wherein the susceptor arrangement is not inductively coupled to the inductive element, and a loaded state wherein the susceptor arrangement is inductively coupled to the inductive element;
• and
• determining, by the controller, the property of the susceptor arrangement from the change in the electrical parameter of the circuit
• wherein the electrical parameter is one of a resonant frequency of the circuit and an effective grouped resistance r of the inductive element and the susceptor arrangement.