Experimental investigation of electromagnetic interference behavior of PCB heatsinks according to feeding point in 1-10 GHz band

Abstract

The miniaturization of the circuit as a result of the increase in the operating frequencies of the PCB circuit elements increases the amount of heat in the environment. Metal heatsinks are widely utilized for the transfer of an increased amount of heat. However, the heatsinks cause radiated electromagnetic (EM) emissions at certain frequencies. These emissions negatively affect the operating performance of the circuit elements around the heatsinks. In this study, the effect of different feeding points on EM behavior of rectangular and circular heatsinks with an equal base area are investigated in the 1-10 GHz band. Reflection coefficient, EM emission, normalized radiation pattern, and E-field distributions are obtained. Simulation and measurement results are compatible with each other. The first resonance frequency for the 1st and 2nd feeding points in the rectangular heatsink is 3 GHz and the reflection coefficient values at this frequency are -10.1 dB and-12.3 dB, respectively. In the circular heatsink, the first resonance frequency for the 3rd and 4th feeding points is 2.2 GHz and reflection coefficient values at this frequency are-14.9 dB and-17.3 dB, respectively. In addition, the radiated emissions for the 1st feeding point in the 1.3-3.9 GHz and 5.8-10 GHz frequency bands in circular heatsinks should be preferred since they are-2-8 dBmV/m less than other feeding points. In rectangular heatsinks, the emission for the 1st and 2nd feeding points in the 1-2 GHz and 6-10 GHz frequency bands should be preferred since it is-5-6 dBmV/m less than others. As a result, it is recommended that the components be placed in the heatsink center as both heatsinks emit fewer emissions when fed from the center.