The Key Technology Of High Power Active Phased Array Antenna For Efficient Heat Dissipation

Active phased array antenna is the core component of active phased array radar,and it is a comprehensive application of electronic system.It is composed of a large number of active components and electronic equipment.These active components and electronic equipment all use power elements,which are accompanied by a large amount of heat generation when working.In order to reduce the size of the antenna and improve the performance of the antenna,the integration degree and miniaturization of the active components are continuously improved,and the thermal load,installation distribution density and power consumption of the power components in the components are also increasing rapidly.High integration and miniaturization will cause the temperature of active components to rise while working.Any active components will fail or fail under the condition of long-term high temperature environment or uneven temperature distribution.Efficient heat dissipation design for high power active phased array antenna has become the key to the further development of antenna performance.In this paper,a high-power active phased array antenna and a T/R module chip are taken as the research objects,aiming at the maximum temperature and temperature distribution of the antenna,the cooling effect of the third-generation heat dissipation scheme is studied.According to the location of the heat dissipation medium and the size of the heat dissipation capacity,the commonly used heat dissipation scheme can be divided into three generations.The first generation of heat dissipation method is the external heat dissipation of the components,and the heat dissipation capacity can be achieved200W/cm~2.The second generation heat dissipation method is component immersion heat dissipation,the heat dissipation capacity can be achieved 500W/cm~2;The third generation heat dissipation method is the internal heat dissipation of the component chip,and the heat dissipation capacity can reach above 1000W/cm~2.In view of the external heat dissipation scheme of the first generation components,the heat dissipation method of heat pipe+cold plate is adopted.A"U"shaped heat pipe is designed in the middle of the vertical heat source.The cold plate directly contacts the heat source,and the heat pipe is cooled by the external fin radiator.The finite element model of heat pipe cooling plate of active phased array antenna was built to calculate the temperature distribution of the antenna when heat pipe+cold plate cooling mode was adopted.When the antenna is working,the temperature field is distributed horizontally and asymmetrically,and the maximum temperature of the antenna is 39.6℃.The maximum temperature of heat pipe and cold plate is 30.3℃ and 30.8℃,respectively.After adopting the heat pipe+cold plate cooling mode,the maximum temperature of the antenna is reduced by 0.4℃,with a drop rate of 1.1%.In view of the second generation module’s submersion cooling scheme,the non-conductive fluid submersion cooling method is adopted to study the three commonly used submersion cooling fluids,namely pure water,mineral oil and fluorinated liquid.The phenomenon that the cooling liquid deflects downward under the influence of gravity causes the temperature gradient of the antenna to increase is analyzed and a cooling scheme is proposed to increase the uniformity of the cooling liquid velocity by adding a diversion block in the sealed coolant box.The finite element model of non-conductive fluid immersed heat dissipation of active phased array antenna is constructed to calculate the temperature distribution of the antenna when the non-conductive fluid immersed heat dissipation is adopted.When the antenna is working,the temperature field is distributed longitudinally symmetrically and laterally asymmetrically.The maximum temperature of the antenna is 21.9℃.The maximum temperature of the antenna is reduced by 18.2℃ after heat dissipation measures are applied,and the temperature drop reaches 45.4%.The temperature of the electronic components in the antenna feed layer decreases greatly,and the temperature inhomogeneity of the antenna radiation layer basically disappears.In view of the internal heat dissipation scheme of the third generation module chip,the embedded heat dissipation method is adopted to study the embedded heat dissipation scheme of PCB direct etching coolant microchannel and diamond substrate etching coolant microchannel.A cooling scheme was put forward to install diamond substrate under PCB,coolant flowed into the middle part of the substrate and out of the four corners,and coolant jet radiated in the middle part of PCB.The finite element model of embedded heat dissipation of high-power chip was built to calculate the temperature distribution of the antenna when the embedded heat dissipation of diamond substrate was adopted.The maximum temperature of the chip is 20.5℃.When the chip is working,the temperature gradient of PCB board is small,the middle part is affected by the direct jet of coolant,and the temperature is obviously lower than the surrounding.The maximum temperature of the chip is reduced by 41.5℃ by using the embedded cooling scheme,and the cooling rate is 66.9%.