Application of incremental length diffraction coefficients to calculate the pattern effects of the rim and surface cracks of a reflector antenna

The authors demonstrate the importance of incremental length diffraction coefficients (ILDCs) for accurately calculating the pattern of reflector antennas and for investigating the effect of cracks on the surfaces that can result from the imperfect fitting together of panels to form a large reflector. The three models of cracks considered here are 1) an infinitely long slit in a PEC (perfectly electrically conducting) screen, 2) an infinitely long channel with a semicircular cross section in a PEC screen; 3) an infinitely long boss (ridge) with a semicircular cross section in a PEC screen. Significant pattern effects of the cracks are found depending on the crack model and on the orientation of the cracks.<>