Voltage tuning of microwave magnetic devices using magnetoelectric transducers

Abstract

Tunable microwave magnetic devices that provide increased performance with reduced size, weight, and cost. The disclosed microwave magnetic devices are voltage-tunable devices that include ferrite substrates. To tune the devices, the magnetic permeability of the respective ferrite substrates is varied by external, voltage-tuned, magnetic fringe fields created by one or more magnetoelectric (ME) transducers.

What is claimed is: 
     
         1 . A tunable microwave magnetic device, comprising:
 a ferrite substrate;   a micro-strip circuit formed on the ferrite substrate; and   at least one magnetoelectric (ME) transducer,   wherein the ME transducer is operative, in response to a voltage applied across the ME transducer, to create an external magnetic fringe field emanating from the ME transducer, the external magnetic fringe field effectively penetrating the ferrite substrate for tuning the microwave magnetic device.   
     
     
         2 . The device of  claim 1  wherein the ME transducer includes one or more piezoelectric layers, and one or more magnetostrictive layers, each of the one or more magnetostrictive layers being bonded to at least one of the one or more piezoelectric layers. 
     
     
         3 . The device of  claim 2  wherein at least one of the one or more magnetostrictive layers is disposed in the plane of the ferrite substrate. 
     
     
         4 . The device of  claim 2  wherein at least one of the one or more magnetostrictive layers is disposed in contact with the ferrite substrate. 
     
     
         5 . The device of  claim 2  wherein the one or more magnetostrictive layers are implemented using Terfenol-D. 
     
     
         6 . The device of  claim 2  wherein the one or more piezoelectric layers are implemented using lead magnesium niobate-lead titanate (PMN-PT) single crystal. 
     
     
         7 . The device of  claim 1  wherein the ME transducer includes two piezoelectric layers, and a single magnetostrictive layer disposed between the piezoelectric layers. 
     
     
         8 . The device of  claim 7  wherein the single magnetostrictive layer is mechanically coupled to each of the two piezoelectric layers. 
     
     
         9 . The device of  claim 7  wherein the single magnetostrictive layer is disposed in the plane of the ferrite substrate. 
     
     
         10 . The device of  claim 7  wherein the single magnetostrictive layer is disposed in contact with the ferrite substrate. 
     
     
         11 . The device of  claim 2  wherein the voltage applied across the ME transducer creates an electric field in the ME transducer, the electric field producing, via the ME effect, a mechanical strain in the one or more piezoelectric layers, and wherein each of the one or more piezoelectric layers is operative, in response to the mechanical strain, to transmit a force in at least one of the one or more magnetostrictive layers, thereby inducing an effective internal magnetic field within the respective magnetostrictive layer. 
     
     
         12 . The device of  claim 11  wherein the effective internal magnetic field within the respective magnetostrictive layer varies a magnetization state of the respective magnetostrictive layer, and wherein the respective magnetostrictive layer is operative, in response to the varied magnetization state, to create the external magnetic fringe field emanating from the ME transducer. 
     
     
         13 . The device of  claim 1  wherein the ME transducer operates with a high remnant magnetization, obviating a need for external biasing components. 
     
     
         14 . The device of  claim 1  wherein the micro-strip circuit formed on the ferrite substrate is a meander line micro-strip circuit. 
     
     
         15 . The device of  claim 14  wherein the meander line micro-strip circuit is a meander line micro-strip ferrite phase shifter. 
     
     
         16 . A method of tuning a microwave magnetic device, comprising the steps of:
 disposing the microwave magnetic device proximate to at least one magnetoelectric (ME) transducer; and   applying a voltage across the ME transducer to create an external magnetic fringe field emanating from the ME transducer, the external magnetic fringe field effectively penetrating the microwave magnetic device for tuning the microwave magnetic device.   
     
     
         17 . The method of  claim 16  wherein the microwave magnetic device includes a ferrite substrate, wherein the ME transducer includes one or more piezoelectric layers, and one or more magnetostrictive layers, each of the one or more magnetostrictive layers being bonded to at least one of the one or more piezoelectric layers, and wherein the disposing of the microwave magnetic device includes disposing the microwave magnetic device proximate to the ME transducer such that at least one of the one or more magnetostrictive layers of the ME transducer is in the plane of the ferrite substrate. 
     
     
         18 . The method of  claim 16  wherein the microwave magnetic device includes a ferrite substrate, wherein the ME transducer includes one or more piezoelectric layers, and one or more magnetostrictive layers, each of the one or more magnetostrictive layers being bonded to at least one of the one or more piezoelectric layers, and wherein the disposing of the microwave magnetic device further includes disposing the microwave magnetic device proximate to the ME transducer such that at least one of the one or more magnetostrictive layers of the ME transducer is in contact with the ferrite substrate. 
     
     
         19 . A tunable microwave magnetic device, comprising:
 a substrate having a magnetic permeability;   a circuit formed on the substrate; and   at least one magnetoelectric (ME) transducer,   wherein the ME transducer is operative, in response to a voltage applied across the ME transducer, to create an external magnetic fringe field emanating from the ME transducer, the external magnetic fringe field varying the magnetic permeability of the substrate for tuning the microwave magnetic device.   
     
     
         20 . The device of  claim 19  wherein the substrate is a ferrite substrate.