Research And Design Of Bulk Acoustic Wave Magnetoelectric Antenna

To satisfy the higher requirements for the RF front-end in the 5G communication era,the requirements for miniaturization,high efficiency and integration of antennas are getting higher and higher.It has become an urgent problem to find an alternative type of antenna with small size and high radiation efficiency.Form the aspect of operating principle,mechanical antenna overcomes the problems of low efficiency and impedance matching caused by the conduction current in traditional antenna.Bulk acoustic wave magnetoelectric(BAW ME)antenna is a kind of mechanical antenna,which can work in GHz frequency band by using the principle of bulk acoustic wave resonance.Leading universities around the world are turning their attention to it.Now the cognition of bulk acoustic wave magnetoelectric antenna is still in the initial stage.Although it is expected to replace the traditional antenna,there are many theoretical hurdles to solve.In this work,the structure design,electric loss and radiation characteristics of BAW ME antennas are studied furtherly.The main work includes three parts.In this paper,a one-dimensional analytical model of bulk acoustic wave magnetoelectric antenna along the direction of vibration is constructed by using the principle of acoustic resonance.Maxwell’s equation is introduced into the constitutive equation of the material,and by using the formulas of the potential energy,radiated power and Q value of the antenna,the above parameters of the 2-6 layer composite stacked structure bulk acoustic wave magnetoelectric antenna are solved respectively.After mathematical normalization of the analytical results,a conclusion is drawn that the three-layer composite stacked structure has the best performance.Furthermore,the stress field of the magnetostrictive layer inside the BAW ME antenna with 2-6 layer composite stacked structure is simulated by using multi-physical field simulation software.We can result that the three-lay structure is the best choice.Secondly,the electrical loss in the radiation region(magnetostrictive layer)of the bulk acoustic wave magnetoelectric antenna is studied.Because the magnetostrictive layer is generally used as metallic magnetic material containing iron and has high electrical conductivity,when the device works in high frequency magnetic field,it will cause large heat loss of the device and reduce the radiation performance.By combining the current law with the piezomagnetic constitutive equation,the dissipation of potential energy and average radiated power in the magnetostrictive layer caused by the conductivity is studied.To improve the performance of the device,a layer of Al N insulating layer was inserted into the magnetostrictive layer to interrupt the eddy current loop and suppress the eddy current loss.We can find that uniform insertion of three layers of Al N insulation layer of 5 nm thickness can suppress the volume eddy current loss,and the inhibition rate can reach 85.2%.Finally,the radiation performance of the bulk acoustic wave magnetoelectric antenna is modeled theoretically.The piezoelectric effect of the piezoelectric layer and the piezomagnetic effect of the magnetostrictive layer are used to solve the current source and the magnetic current source,and the electromagnetic field equations under the near-field/far-field conditions are constructed respectively.The stress field of piezoelectric layer and magnetostrictive layer in BAW ME antenna is simulated by multi-physical field simulation software.The simulation result is substituted into the theoretical model for calculation.A bulk acoustic wave magnetoelectric antenna operating at 1GHz with a transverse size of 100 m and a longitudinal size of 3.36mhas a radiated power of 0.027 W,an efficiency of 2.7%,a directivity coefficient of 1.73 and a gain of-13 d B.Finally,the effects of device thickness and area on the working frequency and internal stress field of the device are discussed respectively.We can find that the gain can not be continuously improved by increasing the working area of the device infinitely.