With the development of electromagnetic interference protection technique and military stealth technique, absorbing materials have become an important subject of scientific research. In this paper, the principle of metamaterial absorber as well as the classification of absorbing materials is introduced, and the progress of microwave metamaterial absorbers designed for microwave frequencies is outlined. Particularly, theoretic and experimental studies on tunable metamaterial absorbers are summarized, and the development trend of metamaterial in tunable absorbers is prospected.

tunability  /  microwave  /  metamaterials  /  absorber