Application Cases

Experiment Name: Electrostrain Experiment of Magnetoelectric Multiferroic Composite (MME) Materials

Research Direction:Wireless communication has always been an indispensable element in modern information society. In addition to commercial electric antennas, very low frequency (VLF) mechanical antennas have recently become a research hotspot because they combine miniaturization and good radiation efficiency in lossy conductive environments. However, their use is challenged due to relatively limited radiation capability and modulation bandwidth. This study demonstrates an improved high-efficiency magnetoelectric (ME) mechanical antenna based on the magneto-mechano-electric (MME) effect, which is realized through the synergistic effect of piezoelectric-driven magnet motion and reverse magnetoelectric (ME) effect. On the contrary, ME coefficient and radiation measurements indicate that the MME antenna exhibits superior performance to ordinary ME antennas. The oscillating magnet, used outside the ME composite material as an additional vibrating magnetic dipole, enhances the radiation of the mechanical antenna. In addition, digital signal modulation using VLF carrier signals is employed to achieve interference-resistant and attenuation-resistant communication. Given the demonstrative demonstration, the antenna based on the MME effect is expected to provide a new strategy for the improvement of mechanical antennas and shows great potential in communication applications in conductive environments.

It is worth noting that mechanical antennas can also be excited by piezoelectric or magnetoelectric self-resonant mechanical structures, which rely on oscillating electric/magnetic dipoles as radiation sources. VLF transmitters based on high-Q lithium niobate piezoelectric crystal rods have been introduced through direct antenna modulation methods, showing higher radiation efficiency than traditional antennas of the same kind. Moreover, it has been found that the use of high-dielectric constant PZT piezoelectric ceramics can increase the electric dipole density and improve radiation efficiency. The high Q factor of these devices leads to limitations of the antenna due to the trade-off between efficiency and bandwidth. On the other hand, multiferroic magnetoelectric (ME) composites exhibit fascinating phenomena in electromagnetic-electric conversion and are promising for application in various functional devices, including antennas.

In this work, a VLF transmitter based on the magneto-mechano-electric (MME) effect has been designed and demonstrated. The system consists of a fixed PZT/Metglas stack with a permanent magnet attached to its free end. ME coupling characteristics and electromagnetic radiation characteristics have been measured, followed by analog and digital signal transmission tests. Experimental results show that the tip magnet not only provides magnetic bias for the ME composite material, but also generates significant electromagnetic radiation gain due to its vibration. This radiation enhancement caused by the MME effect is expected to provide a promising strategy for the improvement of ME antennas.

Experiment Objective:To model the impedance dependence of the resonant frequency using FEA and empirically measure it to quantify the electromechanical performance of composites with different structures, providing arguments and groundwork for subsequent experiments.

Testing Equipment:ATA-3090B Power Amplifier, Signal Generator, Oscilloscope, MME Antenna, Preamplifier

Experiment Process:An audio voltage signal is input into the power amplifier ATA-3090B, and then the amplified signal is transmitted to the MME antenna. A coil is placed 15 cm away from the cantilever as a receiver. The received signal is amplified and fed into the oscilloscope for observation. When the MME antenna is excited with sine waves of fixed amplitude and different frequencies (0.5, 1, 3, and 5 kHz), the received signal exhibits a sinusoidal response at the same frequency. The experiment process flowchart is shown in Figure 1-1.

Figure 1-1 Block Diagram of the Electrostrain Experiment of ME Composite Materials

Experiment Results:Figure 1-2a respectively describes the relationship between the radiation field strength and power consumption of L-T mode ME composite materials, ME cantilevers, and MME cantilevers. Since the resonant operating frequencies of the composite materials (24.6 kHz, 11.32 kHz, and 11.5 kHz respectively) have far-field regions (kr>>1, where k is the wave number and r is the distance) exceeding 2 km, it is difficult to test the far-field radiation characteristics. A search coil is placed 20 cm along the longitudinal distance from the radiation source, and the antenna is driven at its resonant frequency with 500 mW. The voltage output received from the search coil is divided by the coil's transfer function to obtain the detected magnetic flux density. The radiation field strength generated by the MME antenna is much stronger than that of the L-T mode ME composite materials and ME cantilevers with the same applied power (Figure 2a). As shown in Figure 1-2b, the magnetic flux decreases rapidly with increasing distance, and the T magnetic field can be detected at 5 m. In addition, empirical curve fitting indicates that the measured magnetic flux attenuation is 1/r^3, which is very consistent with the attenuation law of quasi-static magnetic fields.

Figure 1-2 Radiation Performance of ME Antenna. a) B field measured at 20 cm as a function of input power for stress-free L-T mode ME laminates, one-end-clamped ME and MME cantilevers in their resonant states. b) B field distribution as a function of longitudinal distance caused by the MME cantilever with a driving voltage of 20 V, power of 500 mW, and frequency of 11320 Hz.

Figure: ATA-3090C Power Amplifier Specifications

About Aigtek:Xi’an Aigtek is a high-tech enterprise specializing in the research, development, production, and sales of electronic measurement instruments such as power amplifiers, high-voltage amplifiers, power signal sources, preamplifiers for micro-signals, high-precision voltage sources, and high-precision current sources. It provides users with competitive testing solutions. Aigtek has become a widely recognized supplier of instruments and equipment in the industry, with a broad product line and considerable scale. Sample units are available for free trial. For more information on power amplifiers and other products, please continue to follow the official Aigtek website at www.aigtek.cn or call 029-88865020.