Reciprocity Theorem Based RFI Estimation for Heatsink Emission

Heatsinks are widely used to dissipate heat in electronic devices. RF emission from heatsinks and ICs can cause radio frequency interference (RFI) issues. The existence of the heatsink affects the coupling from the noise source to the victim antenna. In this paper, the heatsink RFI problems are analyzed by two methods using reciprocity theorem. In the first method, the heatsink effect is combined with the antenna to derive the transfer function. In the second method, the heatsink can be characterized in both the source side and the antenna side on a closed 6-surface box. The physical insights and comparisons of the two RFI estimation methods based on reciprocity theorem will be investigated. The proposed methods will be utilized on a few numeric simulations for validations.