Design of Circuit-Analog (CA) Absorber and Application to the Leading Edge of a Wing-Shaped Structure

In this study, first, a circuit analog (CA) absorber consisting of a periodic pattern resistive sheet, glass-fiber/epoxy composite as a spacer, and carbon fabric composite was applied to the leading edge of a wing-shaped structure to reduce the echo radar cross section (RCS). This CA absorber was designed in a flat-plate shape through a parametric study that was performed to optimize the device in the X-band (8.2-12.4 GHz). The reflection loss of the fabricated flat-plate CA absorber was measured with an X-band free-space measurement system. The measured reflection loss was -49.5 dB at 10.15 GHz and the -10 dB bandwidth was about 4.2 GHz. When the CA absorber was applied to the leading edge, the measured echo RCS level showed a 15 dB reduction near 10 GHz and a 10 dB reduction in most of the X-band in both polarizations. Surface discontinuity due to gaps between the leading edge and the wing-box was discussed. From the analysis results, it can be seen that the permittivity of the glass-fiber/epoxy composite material used in the CA absorber was in the proper range for application to a wing-shaped structure.