Research On Finite Frequency Selective Surface And Its Application On Radome

Frequency selective surface(FSS) is a kind of artificial electromagnetic materials with spatial filtering function.It usually consists of periodic arrangement of metal resonance patches or metal resonant slots. Because of its excellent frequency selective characteristics, it is widely used in the field of electromagnetic technology. In order to achieve the purpose of reducing the radar cross section, frequency selective surfaces can be applied to the radome to realize out-band electromagnetic shielding. However, in order to satisfy the requirements of aerodynamic and stealth, radome shape present as non-expandable conicoid, which brings serious challenges to the design, modeling, analysis and production of frequency selective surface.Currently, researches on frequency selective surface are mainly concentrated on numerical calculation methods, filter structures and resonance pattern designs. The analysis methods and modeling design of finite curve frequency selective surface has not yet formed a complete theoretical framework, which in turn is the basis of frequency selective surface radome to achieve engineering applications. Therefore, research on finite frequency selective surface and its application on radome are chosen as the research direction. The main research work is as follows.First, the electromagnetic scattering model and the mathematical representation of periodic structures is discussed, and the basic principles and implementation process of the mode matching method is carried out. Second, the electromagnetic properties of finite frequency selective surface are simulated by the method of FDTD. The transmittance and reflectance of the finite frequency selective surface is carried out through the numerical solution of far-field scattering parameters. This work lays the theoretical basis for the design and analysis of finite frequency selective surface. Third, flexible screen transfer technology and laser engraving technology are two common methods to fabricate frequency selective surface radome(FSR). Some errors are introduced to the FSR during the flexible screen transfer process. The effect to the transmission and stealth characteristics of FSR due to the errors is analyzed. At last two spatial modeling methods that can be used in laser engraving technology are created.In order to analyze the effect to the transmission and stealth characteristics of FSR by the flexible screen transfer technology, the equivalent plate method is used to present errors appearing during the fabrication process onto the FSS plate. The FSS plate is tested by the free-space method. By analyzing the test data, the different influence to the FSR of different introducing errors is summarized. The experimental evidences for FSR by flexible screen transfer technology are provided.Laser engraving technology is a common method for artificial production of three-dimensional structures. However, the technical bottleneck of this approach is that there is not yet a perfect array-modeling method for FSS applied to non-expandable conicoid. Based on the principle of quasi-periodic, a quasi-periodic array-modeling method is developed which can be used to any non-expandable conicoid. By analyzing the RCS, transmittance, reflectance and other parameters of different modeling methods, the feasibility and reliability of quasi-periodic array-modeling method is proved.In order to obtain more accurate strike capability, radar/infrared dual mode guidance has become a development trend of guidance technology. For dual mode guidance FSR, not only achieving electromagnetic shielding is needed, but also a high transmittance in infrared detection band. In response to this demand, a kind of optically transparent frequency selective surface is designed. By the research of its optical characteristics and electromagnetic transmission characteristics, an optimization design method for optically transparent frequency selective surface is developed. An effective technical solution for the stealth of dual mode guidance weapon is proved.