An Eigenvalue Perturbation Solution for the Multiphysics Simulation of Antenna Strain Sensors

To simulate the behavior of a passive antenna strain sensor, current multiphysics coupled simulation (between mechanics and electromagnetics) has mainly adopted the frequency domain solution. For every frequency point in the sweeping range, the frequency domain solver computes the value of scattering parameter S
₁₁
. The S
₁₁
curve is used to identify the new resonance frequency when the antenna sensor is at certain strain level. As a result, the frequency domain solution is computationally expensive. In this study, an eigenfrequency solution, whose efficiency is shown to be much higher than the frequency domain solver, is proposed to directly detect changes of antenna resonance frequency under strain. Toward the eigenfrequency solution, cavity and partially air-filled cavity FEM modeling techniques are proposed to reduce the number of degrees of freedom. In addition, by formulating the eigenfrequency solution as an eigenvalue perturbation problem, Rayleigh quotient iteration and the inverse power iteration method with Rayleigh quotient are proposed to further improve the computational efficiency. The proposed methods will greatly improve the efficiency of antenna sensor designs.