On the Contribution to the Field of the Nonphysical Characteristic Modes in Infinite Dielectric Circular Cylinders Under Normal Excitation

Here, a detailed analysis of characteristic modes and fields of an infinite dielectric circular cylinder when computed through the Poggio-Miller-Chang-Harrington-Wu-Tsai formulation is carried out. The purpose is to determine their contribution to the total field, inside and outside the dielectric body and under two possible excitations: incident plane wave or electric line source within the cylinder. The study has been done analytically to provide necessary physical insight of the results obtained. New details about the so-called nonphysical modes are provided. It is found that these modes, that can be neglected outside the dielectric body, do have a significant contribution to the inner field when the excitation source is within the dielectric body. It is concluded that the terms physical and nonphysical characteristic modes should be replaced for radiating and nonradiating characteristic modes.