  In this work, simulation-based equations to calculate propagation constant in
uniform or periodic structures (SES) are deduced and verified through
simulations in various types of structures. The modeling of those structures
are essentially based on field distributions from a driven-mode solver, and the
field distributions are used as the input parameters of the FPPS. It allows the
separation of forward and backward waves from a total wave inside such a
uniform or periodic structure, and thus it can be used to calculate the
propagation constants inside both uniform and periodic structures even with a
strong reflection. In order to test the performance and function of the FPPS,
it has been applied to a variety of typical structures, including uniform
waveguides, lossfree closed structures, lossy closed structures, and open
radiation structures, and compared with the results of eigenmode solvers,
equivalent network methods, and spectral domain integral equation methods. The
comparison shows the easy-to-use and adaptable nature of the FPPS. the FPPS.
This FPPS could be also applied to open radiating structures, and even
multi-dimensional periodic/uniform structures.
