Efficient simulation of substrate-integrated waveguide antennas using a hybrid boundary element method

This paper presents a hybrid boundary element method for the efficient simulation of substrate-integrated waveguide (SIW) horn antennas. It is applicable with good accuracy to relatively thin structures with conventional circular ground vias. In the multiscale simulations, a 2-D contour integral method is used for the modeling of the fields inside the structure with numerous vias and a method of moments is used for the radiated fields outside. The contour integral method is extended in this paper by a new waveguide port of finite size based on the unit cell analysis of an SIW segment. Several SIW horn antennas are studied to validate the proposed method in terms of the input impedance, the field distribution on the aperture, and the radiation diagram. The proposed method shows good to reasonable accuracy and has a numerical efficiency which is about 2-3 orders higher than FEM-based full-wave simulations. It is therefore well suited for fast optimizations.