This letter presents a voltage-controlled tunable planar antenna based on few-layer graphene flakes. The antenna consists of a rectangular patch with a shorted microstrip stub connected to the radiating edge, and a graphene pad located at the input of the stub. The proposed design exploits the variation of the graphene resistance by an applied bias voltage. Without any bias voltage, the graphene pad behaves almost as an open circuit, not allowing any current passing and, thus, voiding the impact of the stub. Increasing the bias voltage reduces the graphene resistance, thus increasing the current passing through the pad into the stub. This results in the patch antenna radiating at a different frequency. A prototype operating at the frequency of 5 GHz has been designed and tested, demonstrating a frequency tunability larger than 10% with a limited gain degradation.

This letter presents a voltage-controlled tunable attenuator based on few layer graphene flakes. The proposed structure exploits the variation of graphene resistance with an applied bias voltage. The attenuator consists of a microstrip line, connected to grounded metal vias through graphene pads: when no bias voltage is applied, the resistance of graphene is high and the pads behave as open circuits, causing minimum attenuation. By increasing the bias voltage, the resistance of the graphene pads decreases, connecting the metal vias to the microstrip, thus increasing the attenuation. A prototype operating in the frequency band from dc to 5 GHz has been designed and tested. The measured attenuation ranges from 0.3 to 15 dB at 3 GHz, with a bias voltage ranging from 0 (minimum attenuation) to 6.5 V (maximum attenuation).

This letter presents a voltage-controlled tunable phase shifter based on few-layer graphene. The phase shifter consists of a stub-loaded line, composed of a microstrip line with a stub attached to it through a taper and graphene pad. The bias voltage applied to the graphene pad determines a variation of graphene resistance, which eventually causes the phase change. Without any voltage bias, graphene exhibits high resistance, thus isolating the stub and leading to a low phase shift. As the bias voltage is increased, graphene resistance is lowered, the effect of the stub is more pronounced, and the phase shift is increased. A prototype operating in the frequency range from 5 to 6 GHz has been designed and tested. The measured maximum phase shift obtained is 40°, and the corresponding degradation of the insertion loss is 3 dB.

Ever-increasing proportions of sewage sludge are being generated due to increases in population and urbanization. As a result, the disposal of sewage sludge for use as manure and for other agricultural applications is not sufficient. The use of biochar derived from sewage sludge as a substitute to other carbon fillers was analyzed by performing electrical and morphological characterization. The electrical and microwave characterization of composites filled with sludge biochar was performed. Thermal annealing of biochar makes it conductive and suitable for a variety of electrical and microwave applications. Composite samples of a thickness of 4 mm with 20 wt.% of sludge biochar provided a shielding effectiveness value of almost 10 dB.

Electromagnetic interference (EMI) represents a growing challenge in the modern era, as electronic systems and wireless technologies become increasingly integrated into daily life. This review provides a comprehensive overview of EMI, beginning with its historical evolution over centuries, from early power transmission systems and industrial machinery to today’s complex environment shaped by IoT, 5G, smart devices, and autonomous technologies. The diverse sources of EMI and their wide-ranging effects are examined, including disruptions in electrical and medical devices, ecological impacts on wildlife, and potential risks to human health. Beyond its technical and societal implications, the economic dimension of EMI is explored, highlighting the rapid expansion of the global shielding materials market and its forecasted growth driven by telecommunications, automotive, aerospace, and healthcare sectors. Preventative strategies against EMI are discussed, with particular emphasis on the role of advanced materials. Carbon-based nanomaterials—such as graphene, carbon nanotubes, and carbon foams—are presented as promising solutions owing to their exceptional conductivity, mechanical strength, tunable structure, and environmental sustainability. By uniting perspectives on EMI’s origins, consequences, market dynamics, and mitigation strategies, this work underscores the urgent need for scalable, high-performance, and eco-friendly shielding approaches. Special attention is given to recent advances in carbon-based nanomaterials, which are poised to play a transformative role in ensuring the safety, reliability, and sustainability of future electronic technologies.

This article presents novel tunable microstrip attenuators based on few-layer graphene. The proposed topology consists of a microstrip line sided by pairs of grounded metal vias, with graphene pads located between the microstrip line and the vias. The possibility to control the graphene resistance through an applied bias voltage is exploited with the aim to modify the insertion loss of the attenuators. Several pairs of metal vias are adopted to achieve large tuning range, good input matching, and broadband operation. A systematic investigation of the structure with two, three, and four pairs of vias is presented, along with the experimental validation. Prototypes operating in the frequency range from 1 to 10 GHz and with maximum insertion loss exceeding 60 dB are fabricated and tested.