An improved approach to predict far field for infinite planar structure in FDTD simulations

This paper presents an improved approach to predicting the far fields for infinite planar structures using the finite difference time domain techniques. We have found that the equivalent magnetic current decays much faster than the electric current on the surface of the Huygens´ box above the patch antenna due to the presence of the PEC ground plane. Hence, we suggest that the equivalent principle and image theory should be applied to calculate the far field using only the equivalent magnetic current to reduce the size of the computational domain. The example of a single patch antenna and a patch antenna array are employed to validate the proposed approach.