Origami-based stretchable bi-functional metamaterials: reflector and broadband absorber

Multi-functional microwave metamaterials offer a great solution for active components and modules that are potentially applicable in stealth, energy, and wireless communication systems/devices. However, it is challenging to realize a multi-functional behavior in a cost-effective and simple metamaterial system. This paper proposes and demonstrates a metamaterial inspired by origami building blocks that can be controlled by mechanical stimuli. By mechanically changing folding states, the proposed metamaterial can be switched from an ultra-broadband absorber to a reflector. In the compressed mode, the structure exhibits an absorption of more than 90% in a broad frequency range of 6-16 GHz. The absorption characteristic is insensitive to polarization angles and works with a wide range of incident angles. In the stretched mode, the absorption function is turned off and all the incident waves become reflected. Such origami-inspired metamaterials behave in multiple figures of merit involving bandwidth, frequency of operation, angle of polarization, and incidence.