Traditional transducer design methods in Structural Health Monitoring based on Guided Wave propagation rely on the use of the pin-force model, assuming that a piezoelectric actuator can be modelled as a constant shear stress applied at its edge, whatsoever the frequency generated. However, the assumptions of this model are only validated for infinitely thin piezoelectric elements, weak coupling between the host structure and the transducer, and when the wavelength of the generated guided wave is above the size of the transducer. In this paper, a three-dimensional analysis of guided wave generation by a circular piezoceramic is proposed, taking into account the complex shear and normal interfacial stress profile between the transducer and the host structure. The complex stress profile is extracted from a Finite Element Model and then used as a parameter in the analytical propagation formulation. The influence of piezoceramic actuator dimension, thickness and host structure properties is then assessed numerically.