Reduction of the Line-of-Sight Equivalence Principle

An improvement to the line-of-sight (LoS) approximation of the equivalence principle used in far-field computations is presented. In the original LoS approximation of the equivalence principle, the integral equation uses only the surface currents on the LoS surface, as well as the edge currents on the contour of the LoS surface, which is the replacement of the surface integrals over the shadow part of the surface. Here, we show that the integration over one type of surface current on the LoS surface and edge currents is sufficient, which reduces the resources required for the LoS radiation pattern computations by half. The proposed theory is a rigorous analysis of Love’s Equivalence theory with an introduction of the point-of-symmetry concept. The proposed method makes use of the vector-potential field representation to derive the improved LoS equivalence principle. The proposed approach is validated with the calculation of the far-field radiation pattern of a patch antenna using the Finite Difference Time Domain (FDTD) simulations.