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In this paper, an ultra-wideband, angle and polarization-insensitive laser assisted graphene metamaterial absorber is presented. The design consists of double graphene resistive layers with the combination of three dielectric substrates. The graphene imbedded nano-magnetic material Fe3O4 has been synthesisedby laser direct writing technology, which demonstrates a high degree of uniformity with deviations less than 6% for different designed values of sheet resistance. Numerical simulation and analytical studies were carried out in order to analyze the absorption mechanism. The measured results confirm that the absorber operates from 1.32 to 17.9 GHz with over 90% absorptivity. The absorber achieves 173% fractional absorption bandwidth with a thickness of 0.068λL.

Current artificial magnetic conductor (AMC) designs use metallic patterns on rigid substrates and focus on shapes and sizes of AMC structures, rather than on material performance, which has hindered operation bandwidth and design flexibility. Here, we introduce printed graphene AMC-based broadband and flexible microwave radar absorbers, which not only redirect but also absorb the incident wave so to broaden the operation bandwidth. Contrasting to other reported works, the phase characteristics of the AMCs are realized through the control of the surface resistance provided by printed graphene laminates. We produced a variety of AMC structures, composed of printed graphene circular ring arrays with exactly the same shape and size, but different sheet resistances. By carefully designing the sheet resistance of printed graphene laminates, the optimized anti-phase reflection cancellation between AMCs can be achieved. With printed graphene AMCs and flexible dielectric substrate, the absorber presented in this work has a broadband effective absorption (above 90% absorptivity) from 7.58 GHz to 18 GHz, is polarization insensitive under normal incident and can work at relatively wide incident angles. Furthermore, this absorber is capable of bending easily with notable performance, which makes it ideal for applications with irregular and uneven shapes.

Electromagnetic (EM) radiation pollution is increasing attention due to the popularization of electronic equipment. In recent years, various nanomaterials have been widely designed and developed for the enhancement of their EM interference shielding effectiveness (EMI SE). However, large amounts of reported reviews focus on carbon materials and transition metal carbides (e.g., MXenes), while the applications of metal nanocomposites in EM interference shielding are still suffering from the insufficient systematic analysis. Therefore, this paper provides comprehensive information on material selection, whole structural design, engineering preparation schemes and the latest cutting-edge techniques to elaborate the metal nanocomposites (thickness ≤1 mm) for EMI SE. We firstly describe the principle of EMI SE and structure design. Then we also investigate the material selection based on metals such as silver, copper, nickel, and their combinations with carbon materials or other materials. Finally, we compare the strengths and weaknesses of various preparation schemes and identify the state-of-the-art cutting-edge methodologies.

Screen-printed graphene is integrated with multiple-input multiple-output (MIMO) technology to conquer the most concerned surge in electronic waste caused by the mass deployment of Internet of things (IoT) applications. A flexible MIMO antenna is implemented with simple fabrication process suitable for large-scale production by screen printing graphene highly conductive ink on paper substrate, ensuring high-speed 5G mass data wireless transmission without damaging the ecological environment. This environmental-friendly, low-cost, flexible and conformal MIMO antenna with orthogonal polarization diversity employs co-planar waveguide feed and planar pattern for achieving high space utilization and better integration in most scenarios, for instance, body centric networks and monitoring systems. Excellent performance has been achieved due to the high conductivity of the graphene: the fabricated antenna exhibits an average sheet resistance of 1.9 Ω s q − 1 . The bandwidth of the antenna ranges from 2.22 GHz to 3.85 GHz (53.71% fractional bandwidth), covering 4 G long term evolution, sub-6 GHz 5 G mobile communication networks, 2.5 and 3.5 GHz WiMAX, and 2.4 and 3.6 GHz WLAN. Within this range, the antenna exhibits effective radiation, also its envelope correlation coefficient remains below 0.2 × 10 − 6 , manifesting outstanding signal transmission quality in a variety of wireless networks. This work illustrates a novel aggregation of MIMO technology and graphene printing electronics, enabling cheap accessible and green MIMO antennas to be massively integrated in IoT applications.