A perspective on impedance matching and resonance absorption mechanism for electromagnetic wave absorbing

Broadband absorption is urgently desirable for microwave stealth or photothermal conversion, but is a significant challenge in thin layer applications. Impedance mismatch and undesired dielectric relaxation are the main obstacles to realizing simultaneous resonant absorption at multiple frequency bands. In this perspective, the key issues in broadband absorption are briefly reviewed, which must be addressed by the community to enable microwave absorption promoting and widening. Then, impedance matching coefficient used to identify microwave absorbing ability is highlighted. Finally, an ideal model of dielectric dispersion for carbon-based materials is proposed to be used to design broadband absorbing materials, after deducing the inner nature of the typical quarter-wave resonance absorption existing in absorbers.