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Abstract This paper presents the experimental verification of the tunable characteristics of a ferrite composite right/left handed coupled line coupler. The coupler is designed using two coupled CRLH-CRLH transmission lines. The coupler is designed to demonstrate equal through and backward coupling. The novel coupler has been designed and realized in coplanar waveguide configuration on a ferrite substrate. The tunable characteristics are achieved by changing the applied DC magnetic bias to the ferrite substrate. The measurement results reveal that the coupler's fractional bandwidth can be tuned from 29% to 69% by varying the applied DC magnetic bias from 1000 Oe to 1750 Oe. Within the tunable bandwidth, the maximum backward coupling is −5 dB. The coupler has high forward coupling isolation, close to −30 dB at its centre operating frequency. In addition to its tuning capability, the coupler has the advantages of its compact size; it has the length of 11.5 mm and not-so-tight line separations of 2.5 mm. Furthermore the coupler only requires low DC magnetic bias. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Graphene-based printable inks are advanced and promising candidates for flexible printed electronic devices. To develop large-scale graphene-based highly conductive electronics based on existing printing approaches of the material, it is imperative to scale up its ink production methods and optimize the electrical properties of the printed films. Here, a sustainable approach is reported for preparing high-conductive screen-printing graphene ink by recycling cellulose solvents. The ink uses Cyrene solvent in circulation and produces highly concentrated and conductive graphene ink to conquer the limitation of graphene inks in massive industrial production brought by the high cost of the cellulose solvents. A systematic study of the sheet resistance variation with the number of cycles has been carried out. The average conductivity of the ink can exceed 3 × 104 S m − 1, with only a 2-h shear exfoliation process, which exhibits about the same conductivity of recent works (using toxic NMP solvent, complex centrifugation, ultrasonication, etc.) but with much more straightforward and cost-effective fabrication process. The formulation of graphene inks allows flexible metal-free far-field tag antenna to be screen-printed and integrated with an off-the-shelf sensory chip to achieve battery-free wireless UHF RFID far-field temperature sensing. The high responsiveness, accuracy, and sensitivity of the RFID sensing tag were observed with instantaneous detection of accurate and reliable wireless data transmission. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, we first screen print thin GO laminates on Kapton film and then chemically reduce to rGO with desired sheet resistance by controlling printing cycles and reduction time. The thin rGO laminates have a wide range of conductivity from 2.8 S m−1 up to 1.3 × 104 S m−1, exhibiting excellent consistency of electric performance even after 50000 times bending. Commonly used rGO reduction level characterization methods have been compared with the proposed sheet resistance method. It is revealed that the later has higher variation with reduction time, providing a new method for reduction monitoring of rGO. Benefiting from the tunability of its sheet resistance, the rGO laminate not only can be used in flexible electronic circuits as conductors or resistors, but also highly efficient to absorb microwave radiations with proper design. Therefore, a printed, three-layer, Jaumann structured microwave absorber has been designed, fabricated and characterised. The maximum microwave absorption rate is up to 99.9997% where the −10 dB fractional bandwidth is over 153%, which covers L, S and C bands. Moreover, the fabricated absorber can absorb efficiently even when the incident angle is as low as 20°. Full design procedure, simulation and measurement results are presented. [ABSTRACT FROM AUTHOR]

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 Fe 3 O 4 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 0.068λ L. [Display omitted] [ABSTRACT FROM AUTHOR]