Edge-based FEM analysis for MoM basis functions in a waveguide cross slot

Presents a waveguide cross slot as an antenna to radiate a circularly polarized wave. We propose to use vector eigenmode functions for a waveguide with a X-shaped cross section as unknown current basis functions in an analysis for the cross slot using the method of moments. We can understand the radiation mechanism of a circularly polarized wave in the cross slot from the mode excitation coefficients and accurately include the effect of the wall thickness, which cannot be neglected (for millimeter-waves especially). We calculate the vector eigenmode functions by using edge-based FEM. The amplitude and the orientation can be obtained without any numerical differentiations which are needed in the analysis with node-based FEM. We applied the vector eigenmode functions as the basis functions in the method of moments straightforwardly.