| VLF antennas are widely used in underwater and underground communication systems because of their low frequency and strong signal penetration.However,because of the large size of traditional VLF antenna,the communication system built is not only expensive,but also has low radiation efficiency.To solve the above problems,this paper focuses on the research of the miniature magnetoelectric antenna based on the magnetoelectric heterostructure.Through the physical oscillating electric dipole and magnetic moment to generate electromagnetic radiation,the design and preparation of the magnetoelectric antenna with the size only one ten thousandth of the traditional antenna,low energy consumption and high radiation efficiency are designed and manufactured.At the same time,the output response of the device can be improved and the working frequency range of the device can be broadened under the condition of high output by means of the series and parallel connection between the elements,and the multi-frequency point transmission and reception of the signal can be realized in the very low frequency band.The main research work includes the following aspects:Firstly,PZT and Metglas were used as piezoelectric materials and magnetostrictive materials respectively to design the structure of miniaturized VLF magnetoelectric transceiving antenna,and the influence of different geometrical structure parameters on the transmitting and receiving signal size and resonant frequency of the antenna was studied by finite element simulation.The results show that the miniaturized magnetoelectric antenna can exhibit excellent magnetoelectric response performance in the very low frequency band by using the optimized structure design.Secondly,the theoretical radiation models of the piezoelectric layer and the magnetostrictive layer in the magnetoelectric antenna were constructed respectively based on the dipole radiation model,and the transmitting performance of the magnetoelectric antenna was simulated and analyzed by MATLAB software.The results show that the radiation magnetic field intensity of the magnetoelectric antenna decreases linearly with the third power of distance r,and its radiation pattern conforms to the magnetic dipole radiation law.On this basis,a variety of sizes of VLF magnetoelectric antennas were prepared by epoxy resin bonding process,and their signal receiving and transmitting abilities were tested.The results show that the optimal DC bias magnetic field of the unit magnetoelectric antenna is 4.2Oe,the maximum output of the magnetoelectric response is 248.25 m V at the resonant frequency of 26 k Hz,the maximum response coefficient is 9.93V/cm· Oe,and the detection limit is 0.1n T.When it is used to transmit signals,the radiating magnetic field of the unit magnetoelectric antenna at 1.2 meters is 1.06 n T(input power 10 m W).If a more sensitive receiving antenna is adopted and the input power is increased to 100 m W,the radiating distance of the magnetoelectric antenna will reach 22.85 m,and its radiation law is in line with the magnetoelectric antenna radiation model based on magnetic dipole.Finally,several magnetoelectric units with different connection modes are designed and fabricated,and their output response and high output frequency range are studied.The test results show that the magnetoelectric output response is 1.97 times higher than that of a single unit through three units in series,and the intensity of magnetoelectric radiation signal is about2.6 times that of a single unit.Through the parallel connection of three magnetoelectric antenna units,the working frequency range of the magnetoelectric receiving antenna-3d B is expanded to 1.86 times,and the frequency range of the transmitting antenna-3d B is expanded to 2.18 times,which provides a feasible scheme and technical path for the design and preparation of magnetoelectric antenna arrays in the future. |
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