Wide-angle Radar Cross Section Reduction Of Stealth Structure With Finite Large Frequency Selective Surface

Material stealth is an important way to further reduce the Radar Cross Section(RCS)of targets based on the shape stealth.As a new type of stealth material,the Frequency Selection Surface(FSS)is more diversified in function implementation and has more flexibility in design than traditional materials.At present,most of the researches on FSS are the reflectivity performance of flat plates and the monostatic RCS reduction within a small angle of 30°.In this paper,a wide-angle monostatic RCS reduction is designed for a finite-size flat plate structure using a combination of FSS impedance layer and gradient impedance loading on the edge of the metal reflector.The specific research content is as follows:First,the bistatic RCS scattering lobe pattern is simulated,and the monostatic RCS performance of the FSS absorber structure is analyzed and estimated.Furthermore,the differences in RCS performance of FSS finite-size flat plate structures under different polarizations of HH and VV were compared.The monostatic RCS reduction in the oblique incidence VV polarization wide-angle domain is consistent with its absorption performance,and the monostatic RCS reduction performance outside the 30 ° angular domain of oblique incidence HH polarization is poor.By analyzing and simulating the Salisbury screen model,it is obtained that the different RCS performance of different polarizations of the finite-size impedance loaded absorbing structure is due to the discontinuous scattering of the current at the edge of the lower metal reflector.And point out that HH polarization large angle oblique incidence monostatic RCS is difficult to be improved by enhancing FSS absorption performance.Secondly,it is proposed to reduce the contribution of oblique incidence edge scattering by using the method of processing the edge current of the metal to achieve wide-angle RCS reduction.The physical-optical method is used to derive the relationship between the surface current and the impedance of the resistive film,and the edge current is reduced to zero by gradually changing the resistance value of the resistance.then explore the relationship between the RCS characteristics and the size of the finite-size metal plate loaded with the resistance strips,a metal flat plate with resistance strips is designed with a significant RCS reduction in the wide-angle range of 11-90°,and is basically the same as the monostatic RCS performance in range of 0-10° at 5-10 GHz.On this basis,the gradient resistor stripe with large-angle reduce RCS and FSS with small-angle strong absorption are combined to design a FSS finite-size absorbing structure which achieve the performance that 10 d B monostatic RCS reduction within0-90° for HH polarization,and 10 d B monostatic RCS reduction within 0-80° for VV polarization at 5-10 GHz.