Owing to the recent research a method of estimating transmission coefficients for a waveguide of rectangular cross-section loaded with multi-layered parallel-plane dielectrics is found. Consequently, the analysis of the transmitted and reflected fields in terms of the scattering matrix formalism can be performed explicitly. This article is mainly based on comparisons between real measured and computed transmission coefficients of a waveguide filter. the computation employs analysis of closed-form solutions and numerical multi-parameter optimization. the presented waveguide filter is formed by multi-sectional diaphragms placed in a waveguide of rectangular cross-section. Comparison of the computed and measured transmission coefficients demonstrates that the difference is very low, rather marginal and thus the output of the work is considerably promising.