All of the plots and explanations thus far show reflections at normal incidence. Typically, an electromagnetic wave hits the radome surface at an oblique angle, or in the case of a spherical radome, a continuous range of oblique angles. The transmission characteristics of the radome change with the wave incidence angle and polarization. Electric fields that are parallel to the plane of incidence have much higher transmission than fields that are perpendicular to the plane of incidence.

Aerodynamic radomes used on aircraft and missiles often see high incidence angles. This can result in large amounts of axial ratio degradation for circularly polarized antennas and higher insertion loss. Electromagnetic wave fronts from parabolic antennas located inside spherically shaped radomes see low incident angles at the center of the wave front. Out on the edges however the incident angle becomes higher. If the antenna illumination pattern is symmetric, and the antenna is placed at the center of the spherical radome, the symmetric shape of the radome cancels out axial ratio degradation from the oblique incidence angles seen by the antenna.