Study On Fabrication And Characterization Of Passive Magnetoelectric Power Splitter In Ferrite/Piezoelectric Transformer Composites

Power splitters are widely used in radio communication systems,radar systems,satellite communication systems,test and measurement equipment and other fields due to their non-reciprocal,wideband and phase-balanced characteristics,especially in the RF band range（620MHz-4.6 GHz）to accomplish the distribution and stable transmission of power signals.Traditional power splitting technologies mainly include integrated circuit power splitters,power splitters with feedback circuits and cluster power splitters,etc.However,those attempts are mostly made by introducing aggregate discrete components and active feedback circuits to enhance ports isolation and expand the broadband,active components are poorly expandable and not conducive to miniaturized integration of power splitters,this makes it difficult to eliminate the adverse effects of power supply problems and electromagnetic interference.In view of the above,this article takes the Ni_0.8Zn_0.2Fe₂O₄/Rosen type piezoelectric transformer magnetoelectric composite structure as the research object,and densely wound coils on its periphery to form a six-wire-three-port passive magnetoelectric power splitting device,focusing on the strain transmission of magnetoelectric materials,the two-port impedance of the power splitting device and the output power ratio,mainly covering the following main research contents:（1）Study of the intrinsic impedance response of Rosen-type piezoelectric transformers and the dynamic magneto-mechanical transformation characteristics of ferrite materials,exploring strategies for the construction of magneto-electric power splitting devices with high isolation.（2）To design and build a Lab VIEW-based magnetoelectric automated test system to measure the magnetoelectric response of magnetoelectric composite samples.（3）To investigate further the effect of applied load on the output power of each port of the device and the power splitting ratio.The results show that（1）The impedances of the two ports of the piezoelectric transformer differ significantly at the resonant frequencies of 51 k Hz and 103 k Hz（76.40 kΩ,42.47 kΩand46.97 MΩ,146.63 MΩ,respectively）as measured with the help of an impedance analyzer,and that the impedance difference between the two ports differs by about three orders of magnitude at the same resonant frequency,while,with the help of a non-contact optical measurement system,the maximum dynamic magnetostriction coefficient of the ferrite material is 17.55ppm/Oe at the resonant frequency of 81.82 k Hz,indicating that the impedance differences of the piezoelectric transformer and the high magneto-mechanical conversion capability of the ferrite material are more helpful for the device to obtain higher isolation and conversion efficiency at low frequencies;（2）By building a magnetoelectric automatic test system platform,the magnetoelectric voltage coefficients of the two ports of the magnetoelectric composite sample are measured at H_DC=292 Oe 138.9 m V/cm Oe and 175.2 m V/cm Oe at the optimum magnetic field H_DC=322 Oe,providing clear guidelines for improving the transmission efficiency of the magnetoelectric power splitter;（3）The output signal test system of magnetoelectric power splitter is designed and built.The measured power distribution ratio reaches 3:1 under the optimal load（R=6 kΩ,R=30 kΩ）at the first resonance f=60.21k Hz(P_in=1.85μW).Similarly,at the second resonance f=120.33k Hz(P_in=5.22μW),the power distribution ratio reaches 3:1 under the optimal load（R=5.5 kΩ,R=12 kΩ）.Thus,the progress of related research not only provides new ideas for the design of magnetoelectric functional materials in solid-state power electronic conversion devices,but also has potential applications in areas such as the power supply and control of multi-channel LCD strings.