A tunable electromagnetic wave absorber for uniform reflection modulation in broadband

The development of broadband, tunable electromagnetic wave absorbers with stable reflectivity is crucial for real-time reconfigurable applications, particularly in radar systems. Conventional tunable absorbers often rely on absorption band shifts, which may lead to non-uniform reflectivity profiles. A broadband reconfigurable electromagnetic absorber based on wideband unit configuration is proposed, which enables real-time, uniform control of reflectivity in broad frequency range from 4 to 18 GHz (relative bandwidth 90.9%). Unlike conventional tunable absorbers, which primarily rely on absorption band shifts, the proposed absorber maintains a flat reflectivity profile over the entire frequency range. Furthermore, it exhibits stable absorption characteristics for oblique incidence angles ranging from 0° to 30°. Reflectivity is controlled via the adjustment of bias voltage, and experimental results show excellent agreement with simulation predictions, validating the design. The unique capabilities of this absorber bring great application potential in adaptive display technologies, electromagnetic wave control in communication systems, and dynamic radar systems.