The paper presents a possible tool to predict the stop band behaviour in waveguides, considering them as
a semi-infinite structures. Even with the semi-infinite approximation, the numerical results using the semiinfinite
waveguide hasve a good agreement with the experimental results. And it predicts how much attenuation,
frequency zone, and after how many unit cells the stop band effect is saturated, without the need to model
the whole waveguide.
As the whole waveguide is not modelled, just one unit cell is needed,. tThe numerical models are much smaller,
which represents less human and computer time. To make it even faster a model reduction is applied and the
results of the full model and reduced one have a satisfactory error as shown in the configuration A, Figure
16.
Therefore, the stop band behaviour in a waveguide is fully predicted using the presented method. Possible
further works with the method are:, study the effect of reflections in the stop band using a lightly damped
structure, study the effect of the damping in the stop band, as did by [6]. Others possibilities are, study how
many unit cells are needed between excitation and response to have an almost fully developed stop band
effect and, try to stretch the application for panels modelling them as semi-infinite strips.