基于载体对消方法的缝隙小角域散射特性研究

缝隙散射是隐身飞机散射的重要组成部分，已有的缝隙散射研究并未给出小角域（-30°~30°）入射时缝隙散射的结果。基于叠加原理的载体对消方法应用于缝隙散射源的电磁散射计算中，可以更精确地研究缝隙的电磁散射特性。通过单缝隙板的一维成像验证了载体对消方法的有效性和准确性，然后研究了在10 GHz频率下，缝隙散射在小角域内随宽度、长度的变化规律，以及极化特性。不同缝隙宽度的研究结果表明：在小角域内，当缝隙宽度小于1/4波长时，水平极化下缝隙散射比垂直极化下大，而当缝隙宽度大于1/4波长时，水平极化下缝隙散射比垂直极化下小；当缝隙宽度增大时，缝隙在垂直极化下的雷达散射截面（RCS）增长速度更快。不同缝隙长度的研究结果表明：在小角域内，缝隙电磁散射均值随着缝隙长度（200~1 000 mm）的增加而增加，散射均值的大致范围：-22.2~-8.4 dBsm（水平极化），-27.3~-13.3 dBsm（垂直极化）；在小角域内，2种极化下，可拟合出RCS均值与缝隙长度的关系，得到某一缝隙长度的RCS，可计算出不同缝隙长度对应的RCS的大致范围。

Scattering characteristics of slit based on carrier cancellation method in small angular domain

An important part of the scattering of stealth aircraft is slit scattering. Though researches have done on it, none of them has produced results in small angular domain (from -30° to 30°). This paper applied the carrier scattering method based on superposition principle to electromagnetic scattering computation for more accurately studying the electromagnetic scattering characteristics of slit. The effectiveness and accuracy of carrier cancellation method are verified by one-dimensional imaging of a plate with slit. Statistics of polarization characteristics and variation pattern of slit scattering in small angular domain with the width and length were made at 10 GHz frequency. The study results with different slit width show that, in small angular domain, horizontal scattering is larger than vertical polarization scattering when the slit width is less than a quarter of wavelength; otherwise, horizontal scattering is smaller than vertical polarization scattering. It is also found that the radar cross section (RCS) value of the slit increases faster with the growth of slit width under vertical polarization. The results with different slit length demonstrate that, in small angular domain, the mean value of electromagnetic scattering increases with the growth of slit length (200-1 000 mm) and the approximate range of scattering mean ranges from -22.2 dBsm to -8.4 dBsm in horizontal polarization and from -27.3 dBsm to -13.3 dBsm in vertical polarization. The relationship between RCS mean and slit length can be fitted to obtain RCS with a certain length, and thus the approximate range of RCS with different slit length could be calculated.