A rotable tunable ultra-wideband microwave absorber and simple coding application of gradient structure

Abstract Tunable Microwave Absorbers Can Improve The performance and flexibility of the system. Inspired by the rotation of the fan, we have designed a gradient-structured rotating tunable microwave absorber (GRTMA), which consists of two gradient distribution units on top and bottom. GRTMA has the advantages of good low-frequency performance and ultra-broadband absorption and can switch between double absorption peaks and single absorption peaks by rotating the upper unit. Experimental results have shown that GRTMA can achieve 90% absorption within the 2.56–18 Ghz range, with a bandwidth of 15.44 Ghz. The absorption peak position can be switched by rotation. The simulation results show that different materials can be filled in the upper and lower layers, and the phase difference can be modulated by rotation. This is the basis for coding metamaterials and can be used to enhance the radar cross-section reduction performance of microwave absorbers. Traditional coding metamaterials require pre-designed unit structures with phase differences, and then simulated arrangement to achieve coding effects. Once the arrangement is determined, it cannot be directly changed. Our GRTMA can achieve coding solely through rotation, which greatly improves the flexibility of encoding metamaterials. The feasibility of our gradient-structured rotation encoding was also demonstrated through simple coding experiments in the C-band. Therefore, The GRTMA has extremely high application value in the field of microwave absorption, providing a new direction for the design of tunable microwave absorbers and coding metamaterials.