Broadband In-Band and Out-of-Band RCS Reduction of Antenna Based on Multiple Mechanisms

An antenna array based on multiple mechanisms, which are miniaturization techniques, scattering cancellation and absorptive frequency selective surface (AFSS) loading, is proposed for broadband radar cross section (RCS) reduction. Miniaturized antenna contributes to broadband low-RCS performance, while the average RCS reduction is limited. To address this, the miniaturized antennas are arranged to form a checkerboard-like array for scattering cancellation, effectively reducing the in-band RCS. Additionally, an AFSS unit with a transmission band is designed to absorb incident waves out of the operation band. Simulated and measured results are found in good agreement, indicating a broadband RCS reduction of 1 GHz to 14 GHz with a measured average RCS reduction of 10.9 dB under linearly polarized (LP) normal incidence. While under circularly polarized (CP) normal incidence, a notable RCS reduction within 1 GHz to 14 GHz is also obtained. The RCS performance under LP incidence maintains relatively stable as the incident angle increases up to 40°. Moreover, the antenna exhibits good radiation performance, achieving a measured peak gain of 11.4 dBi with a radiation efficiency of 87.2%.