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The Pythagoras Tree Fractal patch is considered on a SiO2 substrate thickness of 1.5 µm to radiate at four frequencies of 4.975THz, 5.38THz, 6.73THz, and 7.61THz with Voltage Standing Wave Ratio (VSWR) ≤ 2. This is a very creative fractal design of a multiband THz antenna, based on a very thin graphene layer, the study proved a value in terms of high radiation efficiency and high gain, at the level of current research we made a comparison study where the design has evidently huge potential regarding applicability for telecommunication technology in the terahertz regime. The demand for high-performance terahertz (THz) antennas has increased significantly in recent years due to their potential applications in various fields such as medical imaging, security screening, and wireless communications. In this paper, the authors present an analysis of a graphene Pythagoras Tree Fractal (GPTF) antenna with a thin SiO2 substrate for THz regime. The GPTF antenna is designed using a fractal geometry approach, which provides multiple resonant frequencies and enhances the overall radiation efficiency. The thin SiO2 substrate is used to reduce the substrate losses and improve the radiation performance of the antenna. The authors use the Finite-Difference Time-Domain (FDTD) software to simulate the performance of the proposed antenna. The results show that the proposed antenna exhibits high gain, low return loss, and wide bandwidth, making it a promising candidate for THz applications.

An atmospheric pressure low power microwave-induced air plasma source at 2.45 GHz is presented in this Letter. The device was capable of self-igniting air and generating plasma with only 50 W microwave input power and without any extra trigger. Its sustaining power was as low as 10 W, and the gas temperature of plasma tail flame measured by a fiber optic thermometer was about 32 °C. Spectroscopic measurements showed strong O H (A 2 Σ + → X 2 Π) bands at 306–310 nm and oxygen atomic lines O I (3p5P → 3s5S) at 777.1 nm and O I (3p3P → 3s3S) at 844.6 nm. N O − γ (A 2 Σ + → X 2 Π r) from 200 to 300 nm was also detected in this air plasma jet. This portable plasma apparatus offers potential for air plasma applications in the biomedical fields. [ABSTRACT FROM AUTHOR]

Constructing high-quality charge transfer scheme to achieve a higher spatial carrier separation rate could be considered as a crucial but challenging work in semiconductor photocatalysis for environmental remediation. Herein, a Z-scheme SnIn4S8/In2O3 heterojunction with interfacial S–O bond was synthesized via a hydrothermal and subsequent thermal calcination process. The as-obtained photocatalysts were employed to removal ciprofloxacin and Cr(VI) in aqueous solution. As expected, the SnIn4S8/In2O3 heterojunction with an optimal 19 wt% SnIn4S8 content exhibited excellent photocatalytic performance for ciprofloxacin degradation and Cr(VI) reduction under visible light irradiation. The Z-scheme charge transfer route was corroborated by the analytical results from trapping experiments, ESR and DFT calculation. Besides, the interfacial S − O linkage between SnIn4S8 and In2O3 was detected by FT-IR and XPS, which acted as a specific bridge to further modify the Z-scheme manner for charge transmission. This synergy of Z-scheme heterostructure linked with covalent S–O bond significantly boosted the separation of electron–hole pairs. Moreover, the SnIn4S8/In2O3 heterojunction also presented high stability and reusability over five test runs. This work provides an effective strategy on fabricating high-efficiency photocatalysts by constructing intimate Z-scheme heterostructures. [ABSTRACT FROM AUTHOR]

Recombination and redox energy declination of photo-induced carriers in their transfer over photocatalysts cause loss of efficiency in photodegradation of contaminants. Constructing a Z-scheme transfer mechanism of them is considered as a promising approach to boost the photocatalytic activity. Herein, direct Z-scheme CuInS2/Bi2S3 heterojunctions were successfully fabricated by a facile one-step hydrothermal method. The obtained photocatalysts were systematically characterized and used for the photo-reduction of aqueous Cr(VI) under visible light irradiation. The results showed that the optimal composite with a 24 wt% Bi2S3 content exhibited a superior photocatalytic activity, which was 4.12 times greater than that of pristine CuInS2, and subsequent cycling experiments demonstrated its excellent photocatalytic stability. Besides, the direct Z-scheme heterostructure of CuInS2/Bi2S3 was corroborated by trapping experiments and XPS measurement, which effectively facilitated the spatial charge separation and kept the photo-induced electrons with a strong reducing ability in the conduction band of CuInS2, thus resulting in its outstanding photocatalytic performance towards the reduction of Cr(VI). This study provides a feasible strategy to improve the photoreduction performance of CuInS2-based composites for Cr(VI)-containing wastewater treatment. [ABSTRACT FROM AUTHOR]

This paper presents a methodology for building an integrated circuit behavioral model that enables the prediction of its electromagnetic (EM) emissions up to several gigahertz. The model, built upon S-parameter characterization and conducted emission measurements, is used to predict the EM emissions of a commercial 16-bit microcontroller. The emission measurements are performed according to several EM compatibility standards, namely, 1 [ohm]/150 [ohm], surface scan, and transverse EM/gigahertz transverse EM (GTEM) method, and their results show an excellent fit with model predictions. Index Terms--Conducted emission, electromagnetic compatibility (EMC), integrated circuit (IC), integrated circuit emission model (ICEM), measurement standards, microcontroller, radiated emission.

Two different approaches to realizing nonlinear transmission lines (NLTLs) are investigated in detail. In the first approach, the nonlinearity is continuously distributed along the line; in the second, the line is periodically loaded (PL) with discrete nonlinear elements. Measured heterostructure-barrier varactor (HBV) characteristics are used as the nonlinearities in both pulse-compression and harmonic-generation (20-60-GHz tripler) simulations. We point out that the choice of simulation Step size is critical in the case of fully distributed (FD) NLTLs, and should be made sufficiently small that no numerical Bragg cutoff frequency appears. For the frequency tripler considered in this paper, simulations show that with PL (PL) NLTLs, 21% efficiency at 210-mW output power and 30% bandwidth can be obtained, whereas only 4.8% efficiency is possible using FD NLTLs. For pulse compression, we find that when properly matched, the FD NLTLs can deliver pulses that are five times sharper than can be obtained with the PL NLTLs. Measured results for an HBV-based PL NLTL frequency multiplier are reported that agree with our simulations, in particular, the 30% bandwidth. The confirmation of the role of the Bragg cutoff frequency in preventing the generation and propagation of undesired harmonics (this improving the conversion efficiency) is obtained from experimental results carried out from hybrid Schottky diodes NLTL measurements. Index Terms--Harmonic generation, heterojunctions, transmission-line circuits, varactor.

In this paper a defected ground structure (DGS) bandpass filter based on half mode substrate integrated waveguide (HMSIW) technology is proposed. We used vertical double circle complimentary split ring resonator (CSRR) as DGS etched on the top plane of the SIW cavity to constitute a multiple mode resonator and dumbbell DGS etched on the ground plane of the SIW cavity for enhance the filter performance. The taper line is used for transition between microstrip to SIW The simulation results obtained by CST and HFSS show that the proposed filter has a large transmitted bandwidth from 6.2 to 12.7 GHz. The higher simulated insertion loss is about -0.5 dB and the lower return loss is about -48 dB. The size of the designed filter is 60 × 9.8 mm2 which make it more compact compared to other published research works with a size reduction of about 50%. Good rejection are achieved under 6 GHz and upper 13 GHz. The good calculation of taper, the empirical parameters of the filter and the use many DGS cells in the bottom plane allowed us to obtain the good results. Good agreement between CST and HFSS simulation results. [ABSTRACT FROM AUTHOR]