This work mainly deals with the characterization of the delaminations in the fibre-metal laminates as the Glare®. We present a direct model based on Electromagnetic Coupled Circuit Method (ECCM). This model has been improved and coupled with analytical computations to avoid the discretization of the load. The number of unknowns needed for obtaining the sensor impedance variations is reduced and computation of the direct model has been sped up. Thus, an optimization algorithm could be applied to obtain the material physical properties and the delamination geometrical parameters in multilayer materials. The particle swarm optimization (PSO), a recent powerful optimization technique, is then coupled with the direct model in an inversion process, providing the desired parameters. Some examples, linked to aeronautics, are presented: thickness of layers and delamination geometrical characterization in fiber-metal laminate material as Glare®. Experimental results are shown and analyzed in comparison.