A frequency-reconfigurable conformal metastructure absorber with liquid crystal temperature control for RCS reduction†

A conformal metastructure absorber based on temperature-controlled liquid crystal (LC) regulation is proposed, designed to mimic the letter ‘S’ to enhance absorption performance. This S-shaped absorber (SA) achieves an absorption rate greater than 0.9 across the 1.39–18 GHz range for the transverse electric mode, with a relative bandwidth of 171.33%. Its thickness is only 3.472 mm, 0.016 times the maximum wavelength (215.83 mm). The SA demonstrates high polarization insensitivity and angular stability, maintaining stable absorption within an incident angle range of 0°–40°. The absorption mechanism is analyzed through impedance matching theory, an equivalent circuit model, and near-electric field distribution. Additionally, the effect of Gaussian curvature on the SA's performance is examined. Finally, leveraging the strong absorption capabilities, the potential of the SA for radar cross-section (RCS) reduction is explored using a three-dimensional scattering diagram. The RCS of the SA is insensitive to the polarization angle and remains stable within the incident angle range of 0°–30°. Effective RCS reduction is achieved across the range of 7.6–18 GHz. Due to its excellent broadband absorption and RCS reduction properties, the SA has significant potential in applications such as stealth materials and electromagnetic pollution mitigation.