Research On Optimization Of Heat Dissipation Structure Of Active Antenna Unit

With the rapid development of communication technology,5G has entered people’s lives.But the Active Antenna Unit（AAU）is the main reason for the increase in power consumption,so heat dissipation has become the key to restricting its development.For the heat sink outside the AAU,the method of contructal theory is adopted in this paper,and the optimal configuration is obtained.Then,a new type of heat sink structure is obtained by using the method of topology optimization,and the heat transfer performance of traditional radiators such as needle fins,trapezoidal fins and rectangular fins is compared and analyzed.Finally,the thermal design of the whole AAU is carried out,and a heat dissipation structure that satisfies its safe operation is obtained.The main research contents and conclusions of this paper are as follows:（1）Based on the configuration theory,the objective function is to minimize the maximum thermal resistance,and the layer-by-layer optimization method is used to optimize the configuration of theτ-shaped fins.When（（?）₁/（?） ₀）_oo=4.1 and（（?） ₁/（?） ₀）_{o ooo}=0.19,there is an optimal target value（（?）_t）_mmm=45.416.Using the response surface analysis method,when （?）₁/（?）₀=0.194 and （?）₁/（?）₀=6,the optimal target value is（（?）_t）_min=45.2003.The two methods can obtain the optimal configuration of the fins,and the target value differs very little,but the optimal configuration of the fins is quite different.When the configuration optimization is performed with the lowest average temperature as the objective function,there is no optimal configuration,but the thickness of the rib root and the refinement of the fin branches have a great influence on the improvement of the fin performance.（2）Based on the topology optimization theory,with the research goal of minimizing the average temperature,a three-dimensional topology optimization of the cooling teeth is carried out.The topology is then compared with needle fins,trapezoidal fins and rectangular fins heat sinks.The results show that under the same conditions,the average temperature of the topological heat sink is 54.49℃,which is 20.37%,17.73%and 16.4%lower than that of pin rib,ladder rib and straight rib respectively.,and The highest temperature is 56.33℃,which is 19.5%,17.73%and 17.05%lower than the other three fins respectively.（3）According to the working environment and structural characteristics of the AAU,it is determined that the external heat dissipation method is natural convection,and the internal heat dissipation method is passive.In view of the internal heat dissipation of the AAU,chip 1 and chip 2 are respectively dissipated by a vapor chamber and a copper plate,and the optimal area of the vapor chamber and copper plate is determined.Then,taking the lowest surface temperature of the radiator as the optimization goal,20 schemes were designed to optimize the structure of the external radiator.The optimization results show that when the substrate thickness is 5 mm,the tooth height is 42.632 mm,the tooth width is 4.158 mm,and the number of internal heat dissipation teeth is 24,the surface temperature of the heat sink is the lowest.After optimization,the junction temperatures of chip 1 and chip 2 are reduced by 37.96%and 33.75%respectively compared with those before optimization,which has excellent thermal design performance.Finally,the heat dissipation performance of theτ-finned radiator and the rectangular radiator is compared on the whole machine model.Finally,the heat dissipation performance of theτ-finned radiator and the straight-tooth radiator is compared on the whole machine model.The results show that the heat-dissipation performance of the former is better than the latter,which verifies the reliability of the configuration optimization.