The method of minimal autonomous blocks (MAB) is briefly described. A universal code computing reflectivity and transmissivity of discontinuities in waveguide structures was developed on the basis of the MAB method. This technique is applied to the solution of dielectric cylinders, metal ridges and bandpass filters in a rectangular waveguide, as well as on shunt posts in a microstrip line. Special attention was given to E-plane tee junctions in rectangular waveguides; scattering matrices are evaluated and approximated by the proper function with dependence on frequency and branch waveguide height.
