The heat flux boundary condition addresses the temperature variation of the baseplate, which is a relatively large plate of metal with an external temperature distribution. The Solid Mechanics interface is identical to the previous model configuration. The impedance boundary condition for the EM analysis must read the computed temperature from the heat transfer multiphysics coupling. The Multiphysics Node in the Model Builder has a thermal expansion feature, which applies the calculated temperature distribution as a thermal expansion into the Solid Mechanics interface. Two physics interfaces are combined bidirectionally to couple multiple physical phenomena. First, the thermo-structural problem is solved, then the EM problem is solved for the deformed state.

Figure 7

Figure 7 Shift in filter performance showing the simulation of an uneven heat source on the baseplate.

Figure 8

Figure 8 Simulated surface temperature.

 
Figure 9

Figure 9 Deformed aluminum housing from heat expansion.

Although the filter is deformed by the uneven heat source on the baseplate, the filter responses are not significantly affected (see Figure 7). The deformation is less when compared to the ambient temperature change with the uniform temperature distribution, previously simulated. The temperature distribution plots show which areas of the aluminum housing are hotter (see Figure 8) and affected by thermo-structural effects (see Figure 9).

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CONCLUSION

In this article, a conventional EM simulation was extended to include thermo-structural effects on a mmWave filter’s performance. Through multiphysics analyses, the performance of a high speed communication system component, a cascaded mmWave cavity bandpass filter, was shown to be robust under harsh environmental conditions. This modeling methodology can be used to simulate the performance and reliability of many different types of sensitive components and subsystems in extreme operating environments, identifying potential problems early in the development process and saving costly redesigns.

Reference

1.“Understand, Predict and Optimize Physics-Based Designs and Processes with COMSOL Multiphysics®,” COMSOL, Web, www.comsol.com/comsol-multiphysics.