Thermal and solid-mechanics FEM simulation of a microwave spatial power combiner amplifier

This paper describes the Thermal and structural combined simulation on COMSOL Multiphysics of a Microwave (MW) Fin Taper (FT) Spatial Power Combiner (SPC) Power Amplifier (PA), based on rectangular Waveguide (WG). In the SPC based PA's, the captured power is feeded by microstrip transmission lines (μSTL’s) to Monolithic Microwave Integrated Circuit (MMIC) Solid State Power Amplifier (SSPA’s). The power dissipation of the MMIC SSPA’s produces a considerable temperature increase and induces a thermal expansion of both the PA’s and the connected structure, which can alter its desired Electromagnetic (EM) behavior. SSPA’s are composed by driver and ended stage transistors which are been considered as different causes that contribute to the total effects, in order to estimate the reached temperatures in the different areas. The model is organized by using Heat Transfer in solids (HT) and Solid Mechanics (SM) COMSOL modules. Temperature, stress and displacement under operative conditions have been computed.