A large computational effort is required in order to design an octangular double-layered shield that can be modeled by a 3-D numerical model only. Indeed, the conventional optimization methods minimize a cost function by many evaluations of this 3-D model. To reduce the CPU time, an optimization technique is developed-based on sequential quadratic programming-that takes advantage of two other models that are faster but less accurate than the 3-D FEM: a 2-D FEM and an analytical model.