Contribution of the illuminated and shadowed areas in the radiation pattern of on-board antennas

The numerical integration considering shadow and illuminated currents in physical optics (PO), is used to calculate the radiation pattern of antennas on complex structures. This method is used when the antenna is placed a distances less than lambda, lambda, of the structure. The parametric surfaces are used to model the geometry. The contribution of shadow currents present results more similar to the measurements than stationary phase method (SPM) or numerical integration considering only illuminated currents.