Typical Aperture For Stealth Design In Flight Platform Integration

Radar stealth and anti-stealth is the key technology to Stealth platforms in modern electronic warfare.But for the stealthy performance of the platforms is a combination,equipped with a variety of low scattering components with different functions,in order to maintain the function of these low scattering components coupled with process limitations,stealthy flight platform surface inevitably introduced electromagnetic defect structure.In addition to these defect structures,the RCS contribution of the integrated short-wave antenna on the tail cannot be ignored.These electromagnetic defect structures and the integrated short-wave antenna on the tail pose a great challenge to the stealth of the vehicle.The research in this thesis has two main components:One is to collate,summarize and supplement the existing literature representations on electromagnetic scattering and surface currents,and to explain the mechanism of surface current generation in the tangential and normal Poynting vectors of a metal plane of finite size from the level of charge movement.After that,the effect of RCS on the electromagnetic defect structure is modeled according to the distribution and flow of surface currents,and the scattering mechanism of several typical defect structures,including steps,gaps and cavities,is analyzed using the new model,which corresponds to the light window model,the gap structure and the conformal antenna cabin brought by the process limitation.And according to the distribution and flow direction of surface currents in these electromagnetic defect structures,three corresponding RCS reduction measures are proposed: all-round transition structure,filled lossy medium,and partially oriented transition structure.Finally,the algorithm based on Multi-Lelvel Fast Multipole Algorithm(MLFMA)and the real measurement verified the validity of the model.Secondly,the effect of fuselage and antenna tilt on the horizontal incompatibility of airborne shortwave antenna is studied,and then a way to integrate the antenna with the metal skeleton designed as a folded oscillator is proposed and verified.The length of the folded oscillator is only 2m,and the antenna is mounted on the flight platform at a 30°tilt toward the tail.Simulation of the single antenna structure shows that the out-ofroundness is more than 6d B,which cannot meet the requirements of the vehicle for omnidirectional communication.Therefore,the dual antenna installation is further proposed and the omnidirectional communication is achieved by feeding the phaseadjusted directional map.Finally,the simulation results show that: in terms of electrical performance,the antenna can basically cover the omnidirectional gain of about 2d Bi at30 MHz by ±90° of feed phase difference,which basically meets the demand of flight platform for shortwave antenna;in terms of stealth performance,the RCS of single antenna at the center frequency points of four bands,S,C,X and Ku,are-28.57 d Bsm,-33.79 d Bsm,-39.09 d Bsm and-42.69 d Bsm,which basically meet the low RCS requirements of shortwave antennas for flight platforms.