SiC FETs promise high voltage working, high output power and a high impedance level for easy matching in applications at low gigahertz freque cies.RF SiC FETs development has bee supported by practical investigation of dispersio using a pulsed I(V)measurement system,a d by relating the multi-bias S -parameter behaviour of the devices to their material and structural features using a FET simulator.The simulator has been evolved through application i the GaAs industry. Modelling dispersion in all technologies is problematic because,whereas the origin of dispersion an be identified experimentally,the mechanism is ot know in enough detail to include other tha a ge eric model of it in the simulator. Nonetheless,the simulator is useful for interpreting practical device behaviour and for examining the likely performance benefits of any proposed changes to SiC FET structure.