高空超长航时飞行器在宽视域侦察、通信中继、应急救灾等领域具有重要的应用价值，为了实现真正意义上的超长航时飞行，充分利用5.8GHz微波远距传输、低衰减等优势，提出了一种基于地面分布式微波能量驱动的高空无人飞行系统。该飞行系统主要包括飞行端（接收整流天线）、分布式发射端、以及天地互联高精度导引跟踪系统。其中，接收整流天线采用共面波导馈电的微带贴片天线，将接收天线和整流电路分别设计在一层介质基板两侧，整流电路基于共面波导的直通滤波器优化设计，形成圆极化整流阵列，数值仿真表明该方案对微波的转换效率可超过50%。接收整流天线以近似复合夹层结构与机体融合，在机身下部平坦区域形成可替代圆形天线区域，平台在该区域使用后加载-平坦下翼面翼型，外翼段使用优化的高升力翼型，保证了一体化平台的整体效能；发射天线采用化整为零的分布式发射阵列由伺服系统驱动跟踪飞行平台，在18km高空形成微波合成覆盖区，仿真证明波束收集效率最高可达80%以上；跟踪导引采用分布式定位策略，融合扩展卡尔曼滤波可以实现高空30m定位误差的超高精度定位。设计完成了1：6.7的缩比系统验证试验，利用缩比飞行平台以8m飞行高度穿越80W单一发射天线微波覆盖区，成功实现能量传输，验证了系统设计原理的可行性。
High altitude super long endurance UAVs have important application values in a field of wide view reconnaissance, communication relay, emergency rescue and other fields. In order to achieve true super long endurance flight, a high-altitude unmanned flight system based on ground distributed launched microwave energy devices is proposed by utilizing the performances of 5.8GHz microwave with long-range transmission and low attenuation. The flight system mainly includes the flight part (rectenna), distributed transmission part, and high-precision guidance and tracking system for the interconnection of heaven and earth. Among which, the rectenna adopts a microstrip patch antenna fed by coplanar waveguides. The receiving antenna and rectifier circuit are designed on both sides of a layer of dielectric substrate. The rectifier circuit is optimized based on a direct through filter of a coplanar wave-guide, forming a circularly polarized rectifier array, and the conversion efficiency of microwave to direct current is simulated to be exceed 50%. The rectenna is fused with the body of the UAV in an approximate composite sandwich structure, forming a replaceable circular antenna area in the flat area of the lower part of the body. An after-loaded airfoil with a flat lower surface is used in this wingbody-rectenna region, and an optimized high-lift airfoil is applied in outer sections of the UAV to ensure the overall efficiency of the UAV. The microwave launched antenna adopts a distributed transmitting array that is divided into several single parts and driven by servo systems to track the flight platform, and composites a microwave coverage area at the altitude of 18km. The simulation data show that the beam collection efficiency of the launched system can reach up to 80%. The tracking guidance system also uses the distributed locating strategy, which can achieve ultra-high precision location of the UAV with an error of 30m combining extended Kalman filtering algorithm at high altitude. A 1:6.7 scaled model has been designed to test the designed system. The scaled UAV with the rectenna arrays fly through the microwave coverage area generated by a single ground launched antenna with 80W total power, and the rectenna successfully achieves and transmits the power of the microwave at a altitude of 8m, which indicates the feasibility of the system.
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