Microwave

Quantum mechanics

Bandwidth (computing)

Materials science

Impedance matching

Absorption (acoustics)

Atomic physics

Telecommunications

Metamaterial

Computer science

Tunable metamaterials

Electrical impedance

Physics

Dipole

Metamaterial absorber

Optics

Resonance (particle physics)

Conceptual design

Diffraction

Human–computer interaction

Proceedings of the National Academy of Sciences

Significance While microwave absorption is a widely pursued topic, a conceptual-based design can offer a theoretical basis for generalization and improvements. We offer a design recipe for ultrabroadband absorption based on the use of electrical dipole resonance in a metallic ring to generate, via interaction with its image resonance, two high-impedance resonances. Impedance matching over the frequency range in between the two resonances is obtained by adding resistance to the metallic ring. To extend the absorption to an ultrabroadband spectrum, we employ a double-layer self-similar structure in conjunction with absorption of the diffracted waves at the higher frequency end. The resulting absorber pushes the overall performance close to the causality limit over a large absorption bandwidth.

Conceptual-based design of an ultrabroadband microwave metamaterial absorber