Pulse delay in wave propagation with composed pupils

A composed pupil system was tested-in the microwave range-in order to verify the possibility of obtaining a considerable reduction in the beam width and a field concentration along the axial axis, as compared to normal pupils. Here we present further experimental investigation, always in the microwave range, in order to evaluate the pulse delay in the propagation. An interpretation of the results is given along the lines of a stochastic model already formulated for wave propagation in the presence of dissipation.