and the same as the detected magnetic field signal respectively a magnetoelectric single element device in transducer or combo mode is shown in fig5 which has a structure similar to that in sensor mode as shown in fig4 except that the invariable field generator is replaced by a variable field generator this variable field generator aims to provide a variable magnetic control field i e a u201c tunable u201d dc magnetic field to the magnetoelectric element so that the device performance such as the conversion efficiency i e the magnetoelectric voltage coefficient u03b1 e operational frequency i e resonance frequency etc can be adjusted by varying the magnitude of this externally applied magnetic control field this unique feature makes the device to be useful in u201c tunable u201d magnetoelectric sensor when operating in its non resonance frequency ranges i e sensor mode in u201c tunable u201d magnetoelectric transducer i e resonator filter switch etc when operating in its resonance frequency ranges and in u201c tunable u201d magnetoelectric combo device when operating in its full frequency range the said variable field generator is preferably but not exclusively an electromagnetic coil in form of a solenoid fig5 a a pair of helmholtz coils fig5 b or the like similar to the case of invariable field generator in fig4 the applied magnetic control field has to be along the desired operational direction of the device i e along the magnetization m axis of the magnetostrictive phase in the magnetoelectric element so as to maximize the device performance but this will be considered as a design option the electromagnetic coils can have any dimensions.