Enhancement of Natural Convection for Cooling Active Antenna Unit Device in 5G Base Station

The Active Antenna Unit (AAU) on the outdoor tower is the key equipment to support the mobile communication of 5G. To suppress the overheating of AAU in summer, effective cooling measures are essential. In the present study, a numerical model of an AAU device with two chips in the outdoor environment was established to explore the surface temperature distribution under a coupling heat transfer process with natural convection and solar radiation was obtained. Moreover, the effects of the fin number, the fin height and the heat flux were discussed on the cooling performance. The results proved that the fins with a number of 12 presented the best cooling performance in this paper. By contrast, increasing the height of fins was still an effective way to improve the cooling performance of fins in outdoor conditions and to resist the thermal shock of chips. Besides, punching through holes on the fins, adding graphite heat spreader and reducing surface emissivity are effective ways to improve the cooling performance. After the optimizations, the maximum temperature decreased by 3.5°C in total. In other words, the contribution of these optimizations to the cooling performance was equivalent to an increase of fin height in 9 mm.