An equivalent circuit for magnetoelectric composites operating in a longitudinal mode resonance: BAW-actuated mechanical antenna

Abstract

It brings new design perspectives to study mechanical antenna in the view of circuit rather than the electromagnetic field. In this paper, an equivalent circuit of bulk acoustic wave (BAW) antenna is constructed by using constitutive relation of magnetoelectric composites and Newton’s governing equation. Based on this circuit, series and parallel resonant frequencies of two phases for BAW antenna are simulated in advanced design system (ADS) and magnetoelectric coupling coefficient is calculated. The results show that the electromechanical coupling coefficient is about 6%, the magnetomechanical coupling coefficient is about 86%, and the magnetoelectric coupling coefficient is about 5.2% under the existing material system (AlN and FeGaB). The magnetoelectric voltage gain is derived based on Kirchhoff’s Current Law, which contributes to studying the influence of the two phases thickness ratio on the performance of BAW antenna. The results show that BAW antenna has the optimal energy coupling and conversion when the thickness ratio of the two phases is 1:1. The input and the output impedances of BAW antenna are calculated by T-parameter matrix, which are perfectly matched with the results in ADS simulation. Relevant experiments have been carried out by preparing the magnetoelectric antenna based on PZT and Terfenol-D materials to verify the universality of the model.