Composite structure design for broadband metamaterial absorption: Integrated nonlinearity and enhanced performance using lumped resistors

A new ultrathin and broadband metamaterial absorber featuring four integrated lumped resistors is presented and examined. The design incorporates nonlinearity to enhance the absorber's performance. This metamaterial absorber achieves broadband absorption, maintaining absorption levels above 90% across the 1.33–3.57 GHz frequency range. The absorber demonstrates simultaneous negative permittivity and permeability, with bandwidths of approximately 670 MHz in the L-band and around 1.57 GHz in the S-band, resulting in a total bandwidth of 2.24 GHz. The fractional bandwidth is an impressive 91%, exceeding the previously reported absorbers. Furthermore, the design is remarkably thin, at 0.097 λ, at the lowest frequency. The absorber, with its fourfold symmetry, is insensitive to polarization angles up to 180° and maintains stable absorption up to 40° for both TE and TM modes. Validation of the design using advanced design system software shows close agreement with the computer simulation technology simulation results. In summary, the proposed absorber, with a FoM value of 1.68 and an effective medium ratio value of 9.09, is highly desirable, offering significant performance benefits, including high absorption efficiency, broad operational bandwidth, and minimal thickness, making it suitable for advanced applications. Finally, the proposed absorber was manufactured and tested to validate the simulation results. The proposed metamaterial absorber offers a flexible and adaptable solution across various fields. It finds applications in radar systems, satellite and wireless communications, environmental sensing and monitoring, stealth technology, and IoT and smart devices.