Effect Of Magnetic Bias Research Articles

Tuning the Performance of Acoustically Actuated Magnetoelectric Antenna via Magnetic and Mechanical Stimuli

Magnetoelectric (ME) antenna operates at the acoustic wave resonance rather than EM wave resonance, thus it shows significant superiority for developing compact antennas and antenna arrays. The simulation of ME antenna involves the nonlinear coupling of Electrostatics, Solid Mechanics, and Magnetic physics, making it difficult to model such devices. This paper proposes a fully multi-field coupled model for the ME antenna, in which the nonlinear magnetostrictive model is taken into account. The nonlinear magnetization is solved and then AC and DC simulations are performed by coupling different physics. The effects of magnetic bias and pre-stress on the converse magnetoelectric (CME) coupling and near-field radiation are discussed for the first time, to regulate the performance of the ME antenna with fixed dimensions. The results indicate that the magnetic bias and pre-stress can change the resonance frequency, CME coefficient, and near-field radiation of ME antenna. Particularly, it should be noted that pre-stress has the opposite effect in the low and high regions of the bias field. The near-field radiation is significantly enhanced by applying a proper magnetic bias or pre-stress. This simulation may facilitate the understanding of nonlinear CME behavior and provide a basis for designing nonlinear active and tunable ME antenna.

Enhanced near-field radiation of acoustic-actuated antennas using embedded magnetoelectric composites

Acoustic-actuated antennas operate at the acoustic wave resonance rather than electromagnetic (EM) wave resonance and thus show a significant superiority for the miniaturization of antennas. This paper designs a new acoustic-actuated antenna using embedded magnetoelectric (ME) composites, to improve the radiations of ME antennas through the enhanced strain transfer at the interfaces between different phases. The performance of the ME antenna is examined through a multiphysics finite element method with considering the nonlinear magnetostrictive model. Then, three optimum schemes are proposed for the improvement of the ME antenna, which are also verified by the simulation results. It has been demonstrated that the EM radiations of the embedded ME composite are effectively improved by changing its sizes or configuration. Due to the magnetic flux and stress concentration effects, the maximum |E| and |H| radiations are respectively enhanced by 88 % and 97 % via using a trapezoidal magnetostrictive layer. The effects of magnetic bias and pre-stress indicate that near-field radiations of the ME antennas with fixed dimensions can be enhanced by external multi-physics fields. This simulation may facilitate the understanding of nonlinear CME behavior as well as provide a basis for the design of tunable ME antennas.

Effect of Magnetic Bias on Nonlinear Scattering by Stacked Semiconductor Layers

The properties of the three-wave interaction and wave scattering by periodic stacks of nonlinear semiconductor layers with external magnetic bias have been explored, taking into account the nonlinear charge dynamics. It has been shown that the mixing processes in magnetoactive semiconductor structures are enhanced by the magnetic bias and the combinations of layer physical and geometrical parameters. The effects of magnetic bias on nonreciprocity of combinatorial frequency generation are discussed.

Microwave properties of composites with chromium dioxide

The permittivity and permeability of composites filled with CrO 2 powder are measured within the frequency range from 0.05 to 12 GHz. A sharp line of magnetic absorption is detected near 8 GHz. The effects of magnetic bias and remanence on the permittivity and permeability spectra are analyzed. The hysteretic behavior of dynamic permeability is observed for both parallel and perpendicular bias orientations relative to the microwave magnetic field. The effect is due to switching of the magnetic texture under bias equal to coercive field. At 50 MHz the parallel bias close to coercive field affects permeability much stronger than the perpendicular one. At 10 GHz the effect of perpendicular bias is higher than that of the parallel one. The effect of remanence on the microwave permeability is negligible. The 3 kOe parallel bias suppresses the line of magnetic absorption and decreases the conductivity of the composite and its microwave permittivity. This can be attributed to the magnetostatic interaction of inclusions in the vicinity of the percolation threshold.

Effect of Magnetic Bias on Acoustic Vibration Element Using Giant Magnetostrictive Material

This paper deals with the effect of magnetic bias on an Acoustic Vibration Element using Giant magnetostrictive material (AVEG), used as is a low frequency transducer for ocean acoustic tomography systems. By measuring the magnetostriction characteristics, it is shown that magnetic bias applied using a magnet is effective, and that the dynamic range must be less than I=±1 [A]. The authors analyzed the magnetic circuit of AVEG and calculated the value of the magnetic bias field. The structure of the magnetic circuit was evaluated in terms of the variation rate of flux density in the vibrator, the effective rate of flux, and the magnetostriction sensitivity.