Yang Shi

Conventional low-frequency antennas face a trade-off between miniaturization and radiation efficiency due to wavelength limitations. Although magnetoelectric (ME) antennas can overcome the electrical size constraint, existing designs lack structural tunability and performance enhancement. This paper proposes a Bézier curve-based (BCB) ME antenna that features a variable cross-section, introducing a shape tuning factor for precise geometric configuration. Using the lumped-mass method, the functional relationship between resonant frequency and the shape tuning factor is derived, establishing the theoretical basis for frequency tuning. A nonlinear multi-field coupled numerical simulation model is established for performance prediction. The BCB structure modifies internal stress distribution, enabling spatial reconstruction of magnetization modulation. The proposed design is validated by comparing the analytical model with our simulation results and literature-reported experimental data. Results show that the BCB design reduces resonant frequency and enhances converse ME (CME) coupling and far-field radiation without increasing material volume. Under clamped and free boundary conditions, the minimum resonant frequencies reach 7.2 kHz and 11.1 kHz, respectively, with CME coupling improved by 124% and 140%. When the shape tuning factor proposed in this work is set to 1/2, the proposed design degenerates into a traditional antenna with uniform cross-sections, which verifies the consistency of the established model.

To address the technical challenge of narrow bandwidth in low-frequency magnetoelectric (ME) antennas, existing solutions, which primarily rely on structural optimization, have not favored a compact antenna design. In response to this issue, this paper introduces a novel approach based on a structure–circuit coupling to broaden the bandwidth of ME antennas. By incorporating an inductor into the antenna circuit to induce an additional electrical resonance, which interacts with the antenna's inherent electromechanical resonance, we achieve multiple resonant modes. Through the development of a structure–circuit coupling simulation model, we investigate the impact of circuit parameters on the antenna's resonance characteristics, uncover the mechanism of the multi-resonant mode, and identify optimal parameter conditions. The effectiveness of the proposed method is validated. Our findings reveal that when the added inductor value is 13 mH, the operating frequency band, corresponding to a ME coefficient of 30.11Vcm−1Oe−1 (compared to the coefficient value at the 3 dB bandwidth without the inductor), is expanded by 942%. This research holds the potential to provide new theoretical insights for the optimization of ME antennas.

Surface-mount device (SMD) diodes offer compact size, light weight, and enhanced reliability over traditional diodes but demand higher precision and more complex manufacturing processes. While research often centers on environmental and material factors affecting electronic packaging reliability, the impact of manufacturing processes on device failure is less explored. This study simulates the pin bending process of an SMD diode, analyzing stress conditions on internal structures for two mold design schemes. The distinct geometric features of molds in the two schemes result in different mold motion patterns and contact locations during operation. Notably, comparative analysis reveals that Design Scheme 1 sustains 2.66-fold greater stress concentration in the heat sink structure while demonstrating 2.16-times elevated chip stress levels relative to Design Scheme 2. Through simulation analysis, in conjunction with real-world manufacturing conditions, the primary factors leading to device failure are identified. Under the influence of mold tolerances and processing errors, the chip stress in the SMD diode increases from 23.603 to 188.11 MPa, a value approximately eight times the original stress level. It is emphasized that dimensional tolerances in the production process significantly impact device reliability, and the design of molds must account for these variations. This research offers valuable theoretical insights into ensuring the reliability of pin bending for various SMD devices. Moreover, the simulation outcomes for the SMD diode contribute to a deeper understanding of the internal stresses encountered in other plastic devices during their pin bending stages.

This study developed a comprehensive theoretical analysis model of the radiation performance for asymmetric-structured self-biased ME antennas, based on multi-field coupling modeling. The variables of internal multi-physical fields are integrated into the Maxwell equations, and electromagnetic radiation information is calculated using the dipole method. Based on the magnetization model and Huygens’ principle, the magnetic field distribution and far-field radiation generated by the self-biased ME antenna are calculated in the finite element simulation software, and the proposed analytical model is verified. The proposed model enables rapid and accurate prediction of self-biased ME antenna radiation, providing critical theoretical guidance for advancing asymmetric antenna structure development. The research results reveal that the magnetostrictive (MS) layer serves as the primary radiation source of the self-biased ME antenna. The magnetic field distribution generated in the high-permeability (HP) layer in the free space and in the MS layer presents the phenomenon of flux aggregation. Both the radiation performance and resonant frequency can be controlled by adjusting the bias magnetic field and pre-stress. In addition, the competitive relationship between mechanical and magnetic properties within the HP layer is also revealed, increasing the HP layer thickness from 50 μ m to 150 μ m boosts radiation efficiency and gain.

This paper proposes a theoretical model for the electromagnetic (EM) radiation of magnetoelectric (ME) antennas, considering the eddy current (EC) loss and the quasistatic hysteresis effect. It characterizes the loss characteristics with complex equivalent parameters and innovatively embeds the coupling of classical and anomalous EC losses into the equivalent permeability of the magnetostrictive layer, thus establishing a quantitative link between the EC loss and radiation performance of the ME antennas. The nonlinear quasistatic hysteresis constitutive equation is incorporated into the derived equivalent parameter through the equivalent parameter method. The developed theoretical model of EM radiation is highlighted with a direct comparison with experimental and simulation data that shows their close agreement. The results indicate that the EC loss significantly suppresses the performance of the ME antennas, causing frequency shift, phase angle lag, and performance degradation, while reducing the thickness of the magnetostrictive layer can effectively decrease the internal EC loss of the ME antennas, thus improving their matching and radiation performance. In addition, the influence of the magneto-elastic coupling characteristics and the EC loss effect of the magnetostrictive thin film on the hysteresis behavior is also revealed. The study provides a theoretical foundation for designing the high-performance self-biased ME antennas.

This study developed a comprehensive simulation and analysis framework for magnetoelectric (ME) antenna arrays, seamlessly integrating an equivalent circuit model with a multiphysics coupling model. The resulting model allows for the rapid and effective prediction of the radiation performance of antenna arrays, providing a valuable reference for broadband design initiatives. The research results reveal that by modifying the length of the ME antennas, it is possible to adjust their resonance frequencies effectively while almost maintaining the converse ME coefficient constant. Furthermore, when the ME antenna units are aligned in parallel to create an array, although there is a slight reduction in the radiation field strength, the 3dB bandwidth of Arrays A and B undergoes a substantial expansion, increasing by 210% and 470%, respectively. Moreover, the radiation performance can be optimized by adjusting the length difference between the antenna elements, thereby achieving the optimal 3dB bandwidth when the length difference is set to 1.1mm.

This paper presents a multi-field coupling model for magnetoelectric (ME) antennas, encompassing a ME film, electrode layers, and a substrate featuring a cavity structure. This model accounts for the nonlinear magnetoelastic coupling within the radiation layer and employs a combined DC and AC simulation methodology to capture the antenna's radiation mechanism. Leveraging this multi-field coupling model, performance differences between the ME antenna and an ideal ME composite film are analyzed. By exploring optimization schemes based on multi-physics fields, electrode materials, and structural design, the ME antenna's radiation performance is significantly enhanced. The findings demonstrate that the complete antenna structure, with its increased thickness and cavity design, exhibits a lower resonance frequency and a higher converse ME (CME) coefficient compared to the ideal ME film. The optimal CME effect is achieved under proper external stimuli, leading to a broader 3 dB bandwidth. Expanding the cavity dimensions enhances the CME coefficient by 42% and reduces the resonance frequency due to decreased acoustic wave loss. Adopting electrode materials with higher acoustic impedance elevates the CME coefficient, yet narrows the bandwidth. Conversely, using silver (Ag) electrodes promotes a broader bandwidth. Additionally, ME antenna arrays are designed to broaden the bandwidth by 300%.