Simulation of temperature dependent materials in high-frequency filters using CST STUDIO SUITE™2011

Elements of high-frequency circuits are often subject to high temperatures caused by power losses. If properties of materials comprising these elements depend on temperature, this heating may modify the spectral characteristics of these elements considerably. In the current work a procedure is demonstrated allowing to estimate this effect quantitatively. As an example, a dielectric resonator is considered containing elements with a high temperature-dependent permittivity. A finite difference time domain solver delivers the distribution of losses within the resonator. A finite difference thermal solver utilizes this information for the computation of temperature distribution. The new material permittivity is then computed and the transient computation repeated with the new material properties. S-parameters of the heated filter are compared with those of the "cold" filter. The whole solution strategy is shown, illustrating a new concept developed for coupled computations.