In this article, the type of heatsinks and the horizontal/vertical orientation of them on the printed circuit boards are investigated to reduce electromagnetic interference (EMI) effects caused by the heatsink on the electronic components on the mainboard. The circular, rectangular, and square heatsinks with the equal base area are designed, simulated, and measured in the 1–10 GHz band. All parameters such as the reflection coefficient, electric field values, and radiation pattern are obtained and compared with each other to specify both selection priority of heatsink type and its orientation in a certain frequency range. As a novelty, both the effect of heatsink type and its orientation on EMI performance is investigated to prepare a heatsink selection handout by using simulation and measurement results. While the radiation emission (RE) of the circular type is the lowest between 1.8–3.6 and 5.8–7.8 GHz bands, the RE of the rectangular one is the lowest in 3.6–5.8 and 9.2–10 GHz. Also, for 1–10 GHz range, horizontal orientation is preferred for 10% of the whole frequency region, while vertical orientation is better for 24% regardless of the heatsink type.

中文翻译：

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散热器预选图，可最大程度地减少PCB上的宽带辐射

在本文中，研究了散热器的类型及其在印刷电路板上的水平/垂直方向，以减少散热器对主板上的电子组件造成的电磁干扰（EMI）效应。在1–10 GHz频带内设计，模拟和测量具有相等基面积的圆形，矩形和正方形散热器。获得所有参数，例如反射系数，电场值和辐射方向图，并将它们相互比较，以指定散热器类型的选择优先级及其在特定频率范围内的方向。作为一种新颖性，研究了散热器类型及其方向对EMI性能的影响，以通过仿真和测量结果来准备散热器选择手册。圆形辐射辐射（RE）在1.8–3.6和5.8–7.8 GHz频段中最低，而矩形辐射辐射在3.6–5.8和9.2–10 GHz中最低。同样，对于1–10 GHz范围，无论哪种类型的散热器，都最好在整个频率区域的10％处采用水平方向，而在24％处采用垂直方向更好。