Efficient Integral Equation Technique for Rectangular Waveguide Slot Antenna Analysis

In this contribution, an efficient integral equation (IE) formulation is proposed for the analysis of slot antennas. To solve the IE, the problem is divided into two equivalent subproblems: the first related to the rectangular waveguide component and the second related to the free-space medium. Subsequently, an equivalent surface magnetic current density defined at the discontinuity is used to couple the equivalent subproblems. In order to reduce the total number of unknowns before solving the IE using the method of moments (MoM), the Lorenz gauge Green's functions of the rectangular waveguide and a grounded half space is used respectively for both equivalent subproblems. Furthermore, due to the slow convergence behavior, the Ewald method has been used to accelerate the evaluation of the Green's functions of the rectangular waveguide. Finally, the proposed IE technique has been validated by comparing the results of the radiation pattern and reflection coefficient of a slot antenna with those provided by the commercial fullwave Ansys HFSS software, together with an example from the technical literature, showing good agreement and better numerical efficiency.