# Intelligent Simulation Technology Based on RCS Imaging
## 1 Introduction  
At present, the methods for aircraft simulation at home and abroad mainly include target characteristics simulation [1; 2; 3; 4] and motion characteristics simulation [5; 6; 7; 8]. In order to improve the function coverage of target drones, it is necessary to develop the technology for simulating variable radar scattering characteristics. The commonly used RCS enhancement techniques include: dielectric reflectors, corner reflectors and Luneberg lens reflectors. A Luneberg lens reflector can focus electromagnetic waves and reflect them out with a high gain, and significantly increase the RCS in a specific angular range. Furthermore, the beamwidth can be adjusted according to the size and position of the reflector. However, its disadvantage lies in the high requirements for the process. The corner reflector material is a common metal with low technological level requirements. Its interface stiffness is high, the price is low and it can meet the needs of the target. Therefore, corner reflectors or Luneberg lenses are commonly used to simulate the radar scattering characteristics of targets [9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19]. In China and other countries, Luneberg lens reflectors and corner reflectors have also been subjected to a lot of research in other aspects. The Luneberg lens reflector is also used in the fields of military target aircraft, calibration reflectors, target indicators or simulators, navigation beacons, targets, buoys, etc. For example, the Luneberg lens reflector with a diameter of 0.3 m can simulate a radar target aircraft of a heavy bomber. In civilian use, fisherm's boats are usually equipped with Luneberg lens reflectors, so that our radar can detect them and carry out search and rescue in rainstorm weather. At the same time, Luneberg lens reflectors can also be used as an antenna; the most widely used is in satellite communication systems, because compared with parabolic satellites on the ground, Luneberg lens reflectors can achieve beam control and a large angle range of 120\({}^{\circ}\). They can also focus the incident electromagnetic wave [20]. In addition, many companies have also conducted research on the production of Luneberglens reflectors, and launched many practical commercial products, such as France's high-speed train satellite antenna, Australia's Luneberg lens reflector array, Japan's lens antenna in the new wind measurement radar, and Egypt's Dr. [PERSON] made a multi-feed source helmet lens antenna [21]. In 2005, [PERSON] et al. [22], aiming at the background characteristics of a bridge's water surface, started with changing the RCS value of the bridge's exposure characteristics, and realized the simulation of the bridge's false target by means of a corner reflector array at a suitable position and coating with absorbing materials. In 2009, [PERSON] et al. [23] proposed a decoy array simulation RCS model and calculation method, and calculated the RCS of the angular reflector array of a ship at sea. This method solved the problem of the model complexity and low calculation efficiency relate to the large electrical size. In the same year, [PERSON] et al. [24] established a mathematical model for the approximate calculation of pier RCS, filtering the target area based on structural analysis and using sliding windows for assignment, which effectively reduced the number of local windows involved in the calculation, and set the corner reflector array of an anti-radar fake pier according to the model. [PERSON] et al. modified the diagonal reflector structure and installed a metamaterial absorber to maintain the same RCS distribution characteristics at 8 GHz and 12 GHz, which could effectively cope with radar detection [25]. [PERSON] et al. realized the variable RCS of the corner reflector by rotating the side of the corner reflector, which could simulate objects considerably larger than itself, but it was not possible to simulate complex targets [26]. [PERSON] et al.