Study on thermal characteristics of RF coaxial switch based on finite element method

RF (Radio Frequency) coaxial switches have the advantages of high transmission frequency and high power capacity, and are widely used in aerospace, communications, military, science and medical fields. In this paper, a three-dimensional finite element model of a RF coaxial switch was first proposed. The power loss in the contact system when the switch transmits high frequency and power signals was divided into the conductor loss and the dielectric loss which were calculated separately. It was noted that conductor loss was the main part of power loss. Then, the power loss in the contact system was considered as the heat source and the steady state temperature field of the whole switch was calculated with Ansoft HFSS and Workbench. The temperature rise in a RF coaxial switch was calculated and verified by experimental testing. Finally, the influence of transmission power was examined and it was concluded that the RF performance would downgrade with increasing transmission power and steady state temperature because of the thermal deformation occurring in the contact system caused by the heat stress. The analysis methods and conclusions presented in this study have important theoretical significance and practical value for improving the performance and reliability of RF coaxial switch products.