Frequency Agile Bilayer Metamaterials for Radar Cross-Section Reduction

Metamaterials (MTMs) are synthetic structures known for their ability to control electromagnetic wave propagation, offering innovative solutions for reducing the radar cross-section (RCS) of objects. This paper proposes an agile bilayer MTM to reduce the RCS. Each layer consists of identical agile MTM unit cells embedded with switches to achieve agility. Depending on the switch state, we can obtain two types of unit cells: connected (ON state) and disconnected (OFF state), which exhibit two different behaviors. The switches are controlled using an external command system. By independently adjusting the switching states (ON/OFF) of the two layers, six agile reflection frequency stop bands are generated, corresponding to the four possible configurations of ON–ON, ON–OFF, OFF–ON, and OFF–OFF, and their reflection and transmission ranges are controlled. This design has the capability to control six distinct frequency bands with a − 1- dBm RCS reduction, comprising two bands within the Ku-band (12–18 GHz) and four within the Ka-band (25–40 GHz).