Method-of-moments solver for all-metal corrugated structures. Leaky-mode analysis and open-stopband suppression

A method-of-moments (MoMs) approach is proposed for the modal analysis of two-dimensional (2-D) all-metal leaky-wave structures periodic along one direction. The electric-field integral equations (EFIEs) for both TM and TE polarizations are formulated in the unit cell (UC) by employing a rapidly convergent Ewald representation for the relevant 2-D periodic Green's function. The integral equations are discretized using triangular subsectional basis functions and a Galerkin testing scheme. Effective modal dispersive analyses are developed for a variety of leaky-wave structures. Real proper (bound) modes, as well as complex proper (backward leaky) and improper (forward leaky) modes, are investigated. The proposed method allows for the accurate design and tuning of asymmetric UCs required to suppress the open stopband (OSB), which cannot be easily carried out by means of full-wave simulations with commercial software. Validations are provided through alternative methods and in all cases the presented formulation shows high accuracy and versatility.