A formulation to develop polynomial surrogate models for high frequency structures subject to multiphysics variations in the frequency domain is presented in this paper. The original fine model considers the mechanical stress and the electromagnetic (EM) effects caused by changes in circuit temperature. These effects are calculated in a FEM-based simulator for which we define the electro-thermo-mechanical properties of the metallic and dielectric materials involved. We illustrate our technique by developing a polynomial surrogate model of a microstrip line implemented in COMSOL, where the circuit temperature is varied from -20 to 180 Celsius degrees. Obtained results show a very good match between the multiphysical fine model and the corresponding surrogate.
