Design And Simulation Of Frequency Selective Surface Switchable Screens And Electromagnetic Scattering Characteristics

In order to cope with various ground surface environments of electromagnetic countermeasures with different electromagnetic scattering signature and investigate the regulation of target scattering signature,their integrated stealth of both target and ground surface environment in electromagnetic imaging mode has become one of the important research topics.Since the Frequency Selective Surface(FSS)switchable screen structure can flexibly adjust the microwave reflectivity amplitude,it can also change the electromagnetic scattering signature of the target.Based on this,the design and analysis of the Active Frequency Selective Surface(AFSS)switchable screen structure are extensively carried out,focusing on the regulation rule of the scattering signature of the target,and mastering the integrated stealth imaging signature of the target and the ground surface environment to guide the camouflage stealth engineering applications.The main findings are as follows:At first,from the viewpoints of equivalent circuit,the design method of the AFSS switchable screen structure is systematically studied.The impedance matching switching characteristics of the switchable screen and the adjustment microwave reflectivity of the switchable screens according to the parasitic parameters analysis of the active Radio Frequency(RF)device are discussed.As a result,a novel method of connecting two devices in series is put forward to balance the parasitic parameter effects of active RF devices.Thus,the purpose of changing the dynamic microwave reflectivity of AFSS screen has realized.Secondly,a switchable screen structure with adjustable microwave reflection amplitude under both normal incidence and oblique incidence conditions in the X-band is further examined.This result also meets the requirements of polarization stability.The research results show that the simulation design of screen can dynamically adjust the microwave reflectivity over the range from-20 to 0 d B,which is consistent with the microwave reflectivity of NRL arc methods measurement.Finally,the electromagnetic scattering signature of the typical structure on the ground military target is evaluated by the Inverse Synthetic Aperture Radar(ISAR)imaging tool.The edge scattering mechanism of the typical target composites is extensivelly described in combination with the shaping stealthy technology.To load the switchable screen technology to change the impedence of the active device,the dynamic change of the microwave reflectivity of the switchable screen have obtained.The purpose of controlling the electromagnetic scattering signature of the composite structure from Radar Cross Section reduction has achiveved.At the same time,the electromagnetic scattering signature of the ground surface environment is simulated by using Gaussian function,and the effects of integrated stealth on both the target and the ground surface environment are evaluated through imaging simulation.In summary,the design and analysis of the AFSS switchable screen and control of the target scattering signature have systemically carried out.The imaging mode signature of the integrated stealth of both the target and the environment have further balanced design.