The Technological Maturity of Chinese AESA Technology & Strategic Impacts
中国有源相控阵技术发展状况及其战略影响
Image 1: APG-63(V)2 radar installed on an F-15C. The APG-63(V)2 was the first fighter mounted AESA radar to enter service worldwide. The first American F-15C unit to receive the new radars were stationed at Elmendorf in 2000. In comparison, the first European AESA entered operational service in 2012 and the first Russian AESA equipped fighters (Mig-35) will not enter service until 2016. The initial US technological lead in AESA technology is attributable to substantial investments made in the late stages of the Cold War.
图1：装备F-15C的APG-63(V)2型雷达。APG-63(V)2是世界范围内最先装备战斗机并投入使用的雷达。位于埃尔门多的美国F-15C单位夫于2000年最先接收该新型雷达。相比较而言，欧洲最早列装使用AESA雷达的时间是2012年，而俄罗斯的Mig-35战斗机于2016年前不会装备AESA雷达。美国在AESA技术上的领导地位，完全得益于冷战后期的巨额投资。
Author's Note: During the research process on the J-31’s avionics (for the upcoming Threat Analysis of Foreign Stealth Fighters:J-31 Part II), it became apparent that very few credible, verifiable, and non-speculative English based source materials existed on the subject of PLA fighter radars. Basic information, such the proper name or designation of a radar system is utilized by a particular fighter often varies between sources; performance figures associated with domestically produced radars is even harder to verify. This article's intent was to compile a wide variety of information on expected future developments in Chinese actively scanned electronic array (AESA) radars. Furthermore, the current “Threat Analysis of Foreign Stealth Fighters: Part I Chengdu J-20” is largely dated with respect to developments with the J-20’s avionics suite and this article subsequently provides more up-to-date information on the J-20’s AESA.
作者注：在J-31航空电子设备研制过程中（在《国外隐身战机威胁分析第二部
分：沈飞J-31》中将进行说明），目前尚没有多少足够可信，或经证实，以及非投机性的解放军战斗机雷达资料。一些基础信息，例如装备特定战斗机的雷达系统的名称或型号与其生产厂商有关；中国国产雷达的性能参数很难被证实。本文的主要目的在于收集汇总有关中国有源相控阵雷达未来发展方向的广泛大量信息。此外，当前《国外隐身战机威胁分析第一部分：成飞J-20》中已经对J-20的航电系统的发展状态进行了大量描述，本文随后将提供有关J-20有源相控阵雷达发展的最新信息。
AESA radars represent a significant increase in detection power, reliability, and electronic warfare capabilities when compared to older electronically scanned arrays (ESA) and mechanically scanned arrays (MSA). This article largely focus on more technical aspects of AESAs but the basics of AESAs are cogently detailed by Karlo Kopp in \
对比较早的电子扫描阵列（无源相控阵）雷达和机械扫描雷达，有源相控阵雷达具有在探测性能、可靠性和电子战方面均有大幅提升。本文主要关注AESA技术，但该技术的更详细描述可参考Karlo Kopp的《有源相控阵列——一个成熟的技术》一文。
Three main determinants dictate the maximum number of transmit receiver modules a fighter radar can accommodate: the volume of the aircraft’s nose, the technological maturity of the firm/country’s T/R module packaging technology, and the effectiveness of the radar's thermal management system(s). The volume of the nose is a fairly intuitive constraint, the larger an aircraft’s nose is, the larger the radar can be. For example, the F-15C’s nose cone is able to accommodate the much larger 1,500 T/R element APG-63V(3) radar vs. the F-16C Block 60 with its comparatively smaller nose cone and its 1,000 T/R element APG-80 AESA. Packaging technology refers to how many individual T/R modules can be installed within the finite space usually accomplished by reductions in size of the individual T/R modules. The more technologically advanced a firm’s T/R packaging technology is, the smaller the individual T/R modules will be resulting in an increase density of the layout of T/R modules within the array. Thus, advancements in packaging technology enable engineers to accommodate more T/R modules within the fixed volume of the aircraft's nose.
三个主要因素决定了战斗机雷达可容纳的T/R组件数量：飞机机头的容积容量、T/R组件封装技术的成熟度，以及雷达的热管理系统的工作效率。机头部位的容积是一个相当直观的约束条件，飞机鼻锥部位容积越大，雷达（天线阵面）越大。例如：F-15C的机头鼻锥可容纳具有1500个T/R组件的APG-63V(3)雷达，而
F-16C Block 60只能容纳具有1000个T/R组件的APG-80雷达。通过减小单个T/R组件的体积，封装技术决定了再固定的空间内可容纳的最大T/R组件数量。更加先进的封装技术可制造体积更小的T/R组件，从而提高了阵面上的T/R组件布局密度。因此，在封装技术上的进步，将允许工程师们在固定的飞机鼻锥空间里布置更多的T/R组件。
Image 2: US early production quad packed transmit receiver modules. The United States no longer produces quad channel T/R modules and has since produced single T/R module designs. Less advanced AESAs such as the Zhuk-AE utilize multi-T/R channel designs, it is possible China's first generation of AESAs also utilize a multi-T/R channel design.
图2：早期美国制造的4联装T/R组件。美国不再制造4联装T/R组件，转而制造独立封装的T/R组件。少数先进AESA系统，例如：Zhuk-AE雷达，使用多联装T/R组件封装技术，中国第一代AESA系统可能也使用了多联装T/R组件设计。
Lastly, thermal management systems are instrumental for the operation of high power AESA radars. Unlike MSA systems, air cooling systems are insufficient to prevent heat related system failures and frequent maintenance issues:
最后，热管理系统在高功耗AESA雷达中起到关键作用。与机械扫描（MSA）系统不同，风冷散热系统不足以防止散热相关的系统故障以及由其引起的频繁维
修费用：
“Due to the behavior of microwave transistor amplifiers, the power efficiency of a TR module transmitter is typically less than 45%. As a result, an AESA will dissipate a lot of heat which must be extracted to prevent the transmitter chips becoming molten pools of Gallium Arsenide - reliability of GaAs MMIC chips improves the cooler they are run. Traditional air cooling used in most established avionic hardware is ill suited to the high packaging density of an AESA, as a result of which modern AESAs are liquid cooled.US designs employ a polyalphaolefin (PAO) coolant similar to a synthetic hydraulic fluid. A typical liquid cooling system will use pumps to drive the coolant through channels in the antenna, and then route it to a heat exchanger. That might be an air cooled core (radiator style) or an immersed heat exchanger in a fuel tank - with a second liquid cooling loop to dump heat from the fuel tank. In comparison with a conventional air cooled fighter radar, the AESA will be more reliable but will require more electrical power and more cooling, and typically can produce much higher transmit power if needed for greater target detection range performance (increasing transmitted power has the drawback of increasing the footprint over which a hostile ESM or RWR can detect the radar” – Kopp, 2014 “由于微波发射放大器的特性，T/R组件中发射部分的用电效率典型值小于45%。因此，AESA系统工作期间所产生的大量热量需要耗散，以避免发射部分芯片变为砷化镓“熔炉”——高可靠性的砷化镓微波单片集成电路需配备更佳的散热器。在众多已装备的航电机载设备中所使用的传统风冷技术，并不适用于高密度封装的AESA系统，因此，现代AESA系统采用液冷技术。美国设计研发的聚-α-烯烃（PAO）冷却液是一种合成液压液。典型的液冷系统往往采用一个液压泵驱动冷却液在天线的散热管道中流动，并最终通过冷却液将热量传递给热交换机。这种热交换机可以是类似汽车引擎散热器的风冷器，也可以是安放在油箱中的浸入式热交换器。相比较传统风冷战斗机雷达而言，AESA系统将更加可靠，但同时需要更高的功耗和更苛刻的散热需求，通过发射更高功率电磁波信号，就可以获得更远的目标探测距离性能（但更高的发射功率同样意味着雷达系统可能更早被敌方ESM或RWR设备侦测而暴露）。”-Kopp，2014。