We introduce a simple but general mechanism to realize the dual magnetic resonance exhibiting a broadband negative permeability. A satisfactory explanation, based on the second-order hybridization of symmetric metamaterials, for resonant splitting is given. It is manifested that the geometric correlation plays a vital role in controlling the hybridization strength. Transfer matrix simulations and equivalent circuit model analysis are performed to corroborate our idea. #

An efficient resolution for ultrathin metamaterial perfect absorber (MPA) is proposed and demonstrated in the VHF radio band (30–300 MHz). By adjusting the lumped capacitors and the through vertical interconnects, the absorber is miniaturized to be only λ/816 and λ/84 for its thickness and periodicity with respect to the operating wavelength (at 102 MHz), respectively. The detailed simulation and calculation show that the MPA can maintain an absorption rate over 90% in a certain range of incident angle and with a wide variation of capacitance. Additionally, we utilized the advantages of the initial single-band structure to realize a nearly perfect dual-band absorber in the same range. The results were confirmed by both simulation and experiment at oblique incidence angles up to 50°. Our work is expected to contribute to the actualization of future metamaterial-based devices working at radio frequency.

There is an increased interest to create artificial magnetic metamaterials that show a negative permeability over a wide frequency range. In this paper, we experimentally and numerically demonstrate a broadband negative permeability using symmetric cut-wire-pair metamaterial structures. This finding is based on the second-order hybridization, which is activated by manipulating the correlation between the coupling within a single cut-wire pair and the coupling between neighboring cut-wire pairs. An effective medium analysis is performed to identify the role of the internal and external interactions in the hybridized metamaterials. An extended second-order hybridization scheme is proposed, which describes the electromagnetic response of more complex systems that exhibit an extremely wide band of negative permeability. In addition, the terahertz response of the cut-wire-pair dimer is further explored by scaling down the dimensions of the structures.

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.