Full-wave analysis of leaky modes in 2-D EBG waveguides

Full-wave numerical approaches for the analysis of leaky modes propagating in Electromagnetic-Bandgap (EBG) waveguides composed by multilayered arrays of two-dimensional (2D) cylindrical inclusions have been proposed. A first method based on the lattice sums technique for periodic structures with inclusions of circular section has been suitably adapted to the analysis of modes with complex propagation wavenumbers. The self-contained formulation uses a fast and accurate calculation of the lattice sums, which allows for an appropriate choice of the spectral determination for each spatial harmonic. A further full-wave modal method based on the Fourier Series Expansion in conjunction with perfectly matched layers (PMLs) has been developed, which can take into account cylindrical inclusions with arbitrary geometry of the transverse section. Real and imaginary parts of the propagation wavenumber are calculated with the two proposed approaches for a typical EBG waveguide and a very good agreement is observed in a wide frequency range.