Distorted Reflector Antennas: Radiation Pattern Sensitivity to the Surface Distortions

The high-frequency performance of the reflector antennas is mainly limited by the surface. It has been shown that distortions on different regions of the reflector surface can have different effects on the radiation performance. In other words, degradation of the radiation pattern due to the presence of surface distortions is sensitive to the location and behavior of the surface distortion profile. In this paper, the concept of “sensitivity of the radiation pattern to the surface distortion” has been introduced and quantified. It can be used in the design of different reflector antennas to prevent radiation degradations due to surface distortion. Based on the Physical Optics and variational analysis, the first-order variational of the far-fields with respect to the surface profile is formulated to present the concept of sensitivity. The variational amplitude can be modified to show the concept of sensitivity of the radiation pattern to the distortions on the surface. Reflector antennas with different geometries and feeding methods have different sensitivity plots. Both co- and cross-polarization fields for feed antenna are considered ti be used in the symmetric and offset reflectors, and sensitivity plots are extracted. Sensitivity plots show areas on the surface that have stronger effects on the radiation pattern variations in the region of the main-lobe and the first few side-lobes.