Metamaterial absorbers with excellent absorption properties and real-time tunability are desirable for practical applications. In this paper, we design and numerically investigate a polarization insensitive wide-angle metamaterial absorber with tunable absorption strength formed by finite-length symmetric metallic plates and graphene sheet. This structure achieves a near perfect absorption, and remains highly absorptive with wide incident-angle, higher than 80% at 60^o for TE mode and around 90% at 70^o for TM mode. Absorption strength can be varied between 97% and 52% by controlling the Fermi energy of graphene while the operating frequency remains relatively stable. Also without the presence of a ground plane as in other conventional absorbers, waves outside of the absorption band are allowed to travel through. The absorbing principle and absorption tunability mechanism are elucidated using effective medium analysis and finite integration simulations.

具有优异吸收特性和实时可调性的超材料吸收器是实际应用所需要的。在本文中，我们设计并数值研究了由有限长度对称金属板和石墨烯片形成的，具有可调吸收强度的偏振不敏感的广角超材料吸收体。这种结构实现了近乎完美的吸收，并且在宽入射角下仍具有高吸收性，对于TE模式，在60 ^o时大于80％，在70 ^o时大于90％。对于TM模式。通过控制石墨烯的费米能，吸收强度可以在97％到52％之间变化，而工作频率保持相对稳定。同样，在不像其他常规吸收器那样不存在接地平面的情况下，允许吸收带之外的波传播通过。通过有效的介质分析和有限积分模拟，阐明了吸收原理和吸收可调性机理。