Design of Low RCS Antenna Using Half-H Shaped Planar Slot Antenna Based on Characteristic Mode Theory

This paper describes how to reduce the radar cross-section (RCS) of a half-H shaped antenna based on the theory of the characteristic mode (CM). Four slits were placed in specific locations on the half-H shaped antenna, and the scattering current distributions were observed. RCS was successfully reduced by an average of 3 dB within the operating frequency band. An additional slit was applied to achieve further RCS reduction by suppressing and eliminating the scattered currents analyzed based on the CMs of the antenna. Compared to the original antenna, the maximum RCS reduction of the antenna reached about 10 dB. Two antennas were fabricated, assembled, and measured to verify the effects of the RCS reduction, and the measured and simulated results had good agreement. This paper shows that effective methods can control scattering performance and significantly decrease the RCS while maintaining radiation performance. The steps for using a CM-based scattering analysis for RCS reduction are summarized at the end of the paper.