International Journal of Numerical Modelling-Electronic Networks Devices and Fields最新文献

This study proposes a numerical approach aimed at mitigating electromagnetic field intensities at ground level generated by overhead power lines. The methodology integrates the boundary element method for field evaluation with the ellipsoid method for field optimization, while adhering to critical design and safety constraints. The optimized power line configurations, derived from this integrated approach, achieved significant reductions in both electric and magnetic field magnitudes at ground level without compromising any specified constraints. Moreover, the research findings demonstrate the robustness, efficiency, and practical applicability of the proposed methodology in the design of optimized power lines, offering potential for increased power transfer capability, and decreased environmental and health impacts.

Metallic spheres play a crucial role in industry and their accurate measurement is essential to ensure the safety of industrial production. Eddy current testing (ECT), which is non-contact and non-invasive, provides an efficient and precise approach for the parameter evaluation of metallic spheres. In this paper, we utilize machine learning (ML) methods to invert inductive signals in order to address the inverse problem of ECT, with the aim of reconstructing the radius of a metallic sphere. Datasets containing the radius information of the metallic sphere were constructed based on the simplified analytical solution. The datasets were divided into two parts based on the real part (RP) and imaginary part (IP) features, and the connection between the two features and the radius of the metallic sphere were compared by five classification models. While achieving accurate classification of aluminum and stainless steel spheres with different radius, the models are evaluated to ensure the reliability and validity of the models. The results show that the use of IP data as a classification feature has better accuracy as compared to RP. The K nearest neighbor (KNN) radius classifier has the highest accuracy of 95.5% in aluminum spheres and the random forest (RF) radius classifier has the highest accuracy of 95.9% in stainless steel spheres. In addition, all five classifiers are able to overcome the effect of lift-off on the classification results.

A novel subthreshold drain current model has been developed for a cylindrical gate all-around junctionless transistor with three different gate materials. The proposed device is built with three gate regions of different work functions that effectively reduce the short-channel effects caused by quantum mechanical effects. The drain current equation is solved for all three operating regions to investigate the device switching characteristics and minimize the drain-induced barrier lowering (DIBL), velocity saturation, mobility degradation, and tunneling. It is understood that the triple material gate structure enhances the transport efficiency of the device. The proposed analytical model is validated by comparison with Sentaurus TCAD numerical simulator results and good agreement is found to be achieved.

Various test structures can be used to determine the specific contact resistivity of ohmic contacts. The transmission line model test structure and circular transmission line model test structure are the most commonly used. The analytical expressions of the former are straightforward and effectively describe the electrical behaviour of a contact, while the concentric geometry of the latter eliminates complications during fabrication. In this article, we present a hybrid test structure that combines the advantages of the transmission line and the circular transmission line models. The analytical expressions of the new structure are presented, and its finite-element modelling is undertaken. The effect of contact geometry on this test structure is also discussed. Using the presented test structure, determining contact parameters does not require any error corrections.

The urge of modern communication system is to design and development of the smart antennas with adaptive radiation characteristics. The multifold capabilities of fourth-dimensional antenna arrays can cater that much needed adaptiveness if properly designed. Compared to the conventional arrays, the fourth-dimensional arrays have one added advantage as the ‘Time’ of all the switched-on antenna elements can be managed to generate the required amplitude and phase tapering without even using attenuators and phase shifters. However, one inherent limitation of fourth-dimensional control parameter is the generation of harmonics or sidebands. This article proposes various means of radiation pattern synthesis in fourth-dimensional linear antenna arrays with pulse shifting, pulse splitting, and a combination of both. First of all, the pulse splitting and shifting techniques are combinedly proposed by reducing the sidelobe levels and sideband levels of the beamforming antenna arrays to enhance directivities and efficiencies. Then, this mathematical proposition of the direction finding fourth-dimensional arrays is developed. Finally, broad nulls over a specific angle of arrival region are created for jamming and interference mitigation. For all these cases, the sidelobe level and the unwanted higher-order sideband levels are suppressed to reduce the unwanted interferences and power losses. The optimal time schemes for all the synthesized patterns are generated by proposing a chaos-based soft computing algorithm. The radiofrequency signals at each radiating array element are processed by the optimal time schemes proposed for specific applications. The outcomes are validated and compared with other state-of-the-art works of this domain to prove the competency of the proposed work. The qualitative and quantitative comparisons presented for beamforming array is aimed for a good improvement over other reported works by targeting ultralow (less than −40 dB) sidelobe and sideband levels. For direction-finding array, the proposed idea has also targeted ultralow sidelobes for the main as well as steered beam patterns. Furthermore, the null placement over a region has been aimed to cover more area for jamming and sidelobe reduction for interference mitigation. Overall, the optimal designs proposed for these advanced applications are beneficial for cutting-edge communication systems.

This paper presents a novel method for nonlinear modeling GaAs field-effect transistors (FETs) in a common gate (CG) configuration, which is crucial for the effective design and thorough assessment of RF switch circuits. By focusing solely on a CG-based GaAs FET for RF switch device characterization and modeling, the modeling process is streamlined compared to traditional methods that involve both CG and common source (CS) devices. The direct measurement of both DC and RF characteristics using the CG device enhances the accuracy of model parameter extraction. This approach ensures consistency in model and simulation applications as the CG topology aligns with devices commonly found in RF switch circuits. Moreover, to enhance predictive accuracy regarding the dispersion effect, an improved equation of drain-source current has been incorporated. The empirical validation of the model reveals good agreements in terms of insertion loss, isolation, and output power performance for the CG GaAs FET device, including a wide band single-pole double-throw (SPDT) switch Monolithic Microwave Integrated Circuit (MMIC).