Broadband Low-RCS Metantenna With Integrated Radiation and Scattering Performance Using Characteristic Mode Analysis

This work introduces a novel design methodology for broadband low radar cross section (RCS) metantennas with integrated radiation and scattering performance. The design leverages characteristic mode analysis (CMA) to create four basic elements with similar resonant frequencies but distinct phase responses under plane-wave excitation. These elements are then arranged in an array to achieve broadband radiation through the simultaneous excitation of multiple modes. Concurrently, broadband RCS reduction can be realized by carefully engineering the phase differences between scattering modes across the operating band. To validate the proposed methodology, 4 × 4 and 8 × 8 slot-coupled metantennas were designed and characterized. Measurement results demonstrate that both antennas achieve an impedance bandwidth and 3-dB gain bandwidth exceeding 43.4% while simultaneously providing a 10-dB RCS reduction across the entire operational band.