| With the wide application of information equipment in military and civil fields,the current electromagnetic environment is becoming more and more complex,and electromagnetic stealth technology in military field has received further attention.In order to achieve electromagnetic stealth and reduce electromagnetic interference,frequency selective surfaces and microwave absorbers have become a hot topic.In most scenarios,it is necessary to conform the surface of the frequency selective surface and the microwave absorber,so this paper focuses on the surface conformal method of the frequency selective surface and the microwave absorber.This paper is divided into three parts.In the first part,a plane flexible metamaterial microwave absorber is studied.Based on the equivalent medium theory,a broadband flexible microwave absorber is designed.The absorbing efficiency of the microwave absorber is more than 90%in the frequency range of 2.6-12 GHz.The absorber uses flexible material as the dielectric substrate,and the conformal surface can be realized by the flexible screen transfer method.High resistance surface can be processed by screen printing,which greatly reduces the processing cost compared with welding lumped components.In addition,the absorber has the advantage of polarization insensitivity,which can effectively reduce the radar cross section of the target in the absorption band.In the second part of this paper,the conformal shape of the broadband flexible microwave absorber on the developable surface is studied based on the design of the first part.For the developable surface,we can design a planar flexible microwave absorber and then use the flexible screen transfer method to conform.In this part,the conformal shape of flexible absorber on single curvature surface(cylinder)and variable curvature surface(cone)is studied.The influence of the diameter of conformal cylinder and the size of the apex angle of conformal cone on the performance of conformal absorber is analyzed.A broadband conical conformal absorber is designed,the apex angle of conformal cone is 30~o.The polarization of the absorber is insensitive at 2.6GHz-11GHz,and the lateral RCS is reduced by more than 8dB.The third part of this paper studies the modeling and Simulation of unfoldable surface,and designs two FSS radomes.The first one is to conform the surface on the known undeveloped surface,the conformal surface is a rotating paraboloid,and the frequency selective surface is a Jerusalem cross-band pass frequency selection.The radome designed can effectively reduce the overall RCS while ensuring the gain in the antenna operating band.The second one is to conform the surface on the approximate F-22 fighter nose,and the frequency selective surface is a double-layer Y-aperture frequency selection surface.The designed radar effectively reduces the overall RCS in passband. |
