Scattering by cavity-backed antennas on a circular cylinder using the FE-BI method

Conformal antennas are typically mounted on surfaces which possess some curvature. However, no rigorous design analysis techniques are available for printed antennas on curved surfaces. Hence, most often planar designs are used and thus the curvature is not considered until expensive prototypes are built. The authors present a rigorous finite element-boundary integral (FE-BI) formulation for the analysis of wraparound and cylindrical-rectangular cavity-backed patch arrays on a cylindrical surface. Two consequences of mounting conformal antennas on curved surfaces as opposed to planar surfaces is the effect of curvature and cavity size on the radar cross section (RCS) of the system. The effect of curvature is shown to be polarization dependent due to curvature induced shadowing. In planar arrays, the size of the surrounding cavity affects the overall strength of the scattered field but not its underlying shape. However, for wraparound cavities, creeping waves interact with each other producing interference ripples in the pattern. Both of these phenomena are discussed.