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Large‐area graphene is typically synthesized on rolled‐annealed copper foils, which require transferring to other substrates for applications. This study examines large‐area graphene growth on electrodeposited (ED) copper foils—used in lithium‐ion batteries and printed circuit boards—via plasma‐enhanced chemical vapor deposition (PECVD). It reveals that, for a set plasma power, a minimum growth time ensures full graphene coverage, leading to monolayer and then multilayer graphene, showing PECVD growth on ED copper is not self‐limited. The process also beneficially modifies the ED copper substrate, like removing the surface zinc layer and changing copper grain size and orientation, thus improving graphene growth. Additionally, the study includes high‐frequency scattering parameter (S‐parameter) measurements in a coplanar waveguide (CPW) system. This involves graphene on a sapphire substrate with a silver electrode. The S‐parameter data indicate that the CPW with graphene shows reduced insertion losses in high‐frequency circuits compared to those without graphene. This underscores graphene's role in reducing insertion losses between metallic and dielectric layers in high‐frequency settings, offering valuable insights for industrial and technological applications.

The millimeter wave frequency band has the characteristics of high resolution, high sensitivity, label free, non-invasive [1], etc. Therefore, this detection technology has broad application prospects in the detection of microliter biological liquid samples. This article is based on the design of coplanar waveguides. A stepped interception structure is designed at the center of the microfluidic path of millimeter wave sensors to intercept and capture tumor cells entering the microfluidic path during fluid injection. This structure is used to improve the accuracy of detection by controlling the similar concentration of each cell. This broadband microfluidic sensor is used to measure the S parameters of different biological liquid samples, including tumor cell suspension HepG2 and THP-1 cell suspension (concentration 1E6 cells/mL), and data processing and error elimination are carried out using Matlab software. In the measurement results, the difference in transmission coefficients between different cell suspensions is aroun 0.4dB.

The light scattering properties of sea salt aerosol particles are essential to understand the terrestrial system and its evolution. In this study, the fixed oriented cuboid sea salt particle model is established. And the effect of aspect ratios and spatial orientations on the scattering properties of sea salt particles are investigated by using discrete dipole approximation (DDA) method. Moreover, the results are compared with that of random orientation sphere, cubic and cylinder particle. The results show that, for the particles with discontinuity surface and fixed orientation, the scattering properties of sea salt particles are sensitive to spatial orientation and aspect ratios of the particles. The scattering characteristics of sea salt particles with different spatial orientation and aspect ratios are very different from the results of random oriented sphere, cubic, and cylinder particles, the relative difference of scattering parameters for fixed and random particles can be more than several times. Compared with the random orientation rectangular particles and the equivalent cylinder particles, the scattering phase matrix parameters of rectangular particles with fixed orientation have more different features in the backscattering direction. The results indicate that for the fixed orientation non-spherical particles, the spatial orientation and aspect ratios have a great effect on the scattering properties of aerosol particles. The study maybe provides a comprehensive understanding of the scattering properties for sea salt aerosol in actual ocean atmosphere.

On-wafer S-parameter measurement can be achieved by establishing signal connection channel between vector network analyser and wafer through a probe station. Before 2010, the development of on-wafer S-parameter measurement technologies was relatively slow in China, and it has been using existing foreign technologies for a long time. In the past 10 years, China has been catching up in this field, and continuously narrowing the gap with the world’s advanced level, gradually completing the localization of calibration methods, wafer probes, and on-wafer calibration standards from RF to terahertz, and forming the metrological capability of on-wafer S-parameter measurement equipment. This paper introduces the development of relevant technologies in this field both domestically and internationally, which provides certain guidance for subsequent development.

The S-parameter is an important metric for measuring microwave devices, and the assessment of its uncertainty directly affects the accuracy of device performance measurements. This paper proposed an uncertainty assessment method for on-wafer S-parameter measurements based on the SOLT calibration/de-embedding technique. It analyzed the Type B uncertainty of each measurement, where the uncertainty of the calibration kits is propagated through error model coefficients to contribute to the uncertainty of S-parameter measurements. Based on the transmission line calibration component used for uncertainty assessment, corresponding measurement systems are constructed. Type A and Type B uncertainties are evaluated separately, and combined uncertainty is calculated. The assessment results indicate that the relative uncertainties of transmission coefficients are all below 5%, while uncertainties of reflection coefficients are slightly larger, with amplitude uncertainty at the higher end of the frequency band ranging from 5% to 10%. Overall, the performance of transmission line calibration is deemed good.

The powerful capability of reconfigurable intelligent surfaces (RISs) in tailoring electromagnetic waves and fields has put them under the spotlight in wireless communications. However, the current designs are criticized due to their poor frequency selectivity, which hinders their applications in real-world scenarios where the spectrum is becoming increasingly congested. Here we propose a filtering RIS to feature sharp frequency-selecting and 2-bit phase-shifting properties. It permits the signals in a narrow bandwidth to transmit but rejects the out-of-band ones; meanwhile, the phase of the transmitted signals can be digitally controlled, enabling flexible manipulations of signal propagations. A prototype is designed, fabricated, and measured, and its high quality factor and phase-shifting characteristics are validated by scattering parameters and beam-steering phenomena. Further, we conduct a wireless communication experiment to illustrate the intriguing functions of the RIS. The filtering behavior enables the RIS to perform wireless signal manipulations with anti-interference ability, thus showing big potential to advance the development of next-generation wireless communications. A filtering reconfigurable intelligent surface is presented with sharp frequency-selecting and 2-bit phase-shifting properties, offering to advance the development of wireless communications with anti-interference and signal-manipulation abilities.

Radio frequency (RF) oscillator design typically requires large-signal, high-frequency simulation models for the transistors. The development of such models is generally difficult and time consuming due to a large number of measurements needed for parameter extraction. The situation is further aggravated as the parameter extraction process has to be repeated at multiple temperature points in order to design a wide-temperature range oscillator. To circumvent this modelling effort, an alternative small-signal, S-parameter based design method can be employed directly without going into complex parameter extraction and model fitting process. This method is demonstrated through design and prototyping a 58 MHz, high-temperature (HT) oscillator, based on an in-house 4H-SiC BJT. The BJT at elevated temperature (up to 300 0C) was accessed by on-wafer probing and connected by RF-cables to the rest of circuit passives, which were kept at room temperature (RT).

A minimally-sized, triple-notched band ultra-wideband (UWB) antenna, useful for many applications, is designed, analyzed, and experimentally validated in this paper. A modified maple leaf-shaped main radiating element with partial ground is used in the proposed design. An E-shaped resonator, meandered slot, and U-shaped slot are implemented in the proposed design to block the co-existing bands. The E-shaped resonator stops frequencies ranging from 1.8–2.3 GHz (Advanced Wireless System (AWS1–AWS2) band), while the meandered slot blocks frequencies from 3.2–3.8 GHz (WiMAX band). The co-existing band ranging from 5.6–6.1 GHz (IEEE 802.11/HIPERLANband) is blocked by utilizing the U-shaped section in the feeding network. The notched bands can be independently controlled over a wide range of frequencies using specific parameters. The proposed antenna is suitable for many applications because of its flat gain, good radiation characteristics at both principal planes, uniform group delay, and non-varying transfer function ( S 21 ) for the entire UWB frequency range.

This work presents, the modeling of small signal parameters for Gallium Nitride (GaN) based Buffered Trench Gate (BTG) MOSFET for wireless applications. To improve the device’s performance, hafnium dioxide (HfO 2 ) and silicon dioxide (SiO 2 ) are stacked and placed in the trenched region and simultaneously compared with BTG-MOSFET and its conventional counterpart. The small signal modeling has been performed in terms of Y-parameters (admittance parameters) and S-parameters (scattering parameters) for all three devices and also compared the results. The main aim for selecting small signal parameters is to analyze the behavior of the device for wireless applications at microwave frequencies. Small signal modeling on the proposed device shows the improved results as compared to its conventional counterparts. Thus, results validate the suitable candidature of GaN-BTG MOSFET for high performance wireless application at microwave frequencies.

The paper follows the construction of a planar Yagi Uda antenna and the influence of the geometrical parameters on its characteristic parameters. According to the studies conducted on classical Yagi Uda antennas, modifying their geometrical parameters can lead to the improvement of the antenna function. Thus, the authors will consider modifying the number of directors, the distance between the fed dipole and the first director, the distance between the directors and the length of the directors in an attempt to determine their influence on the antenna’s characteristic parameters. All the results are compared and the similitude between planar and classical antenna is highlighted. Some of the most important antenna parameters were analyzed namely S parameters, gain, directivity, frequency bandwidth and radiation pattern.