Traditional multi-band frequency selective surface(FSS) approaches are hard to achieve a perfect resonance response in a wide band due to the limit of the onset grating lobe frequency determined by the array. To solve this problem,an approach of combining elements in different period to build a hybrid array is presented. The results of series of numerical simulation show that multi-periodicity combined element FSS,which are designed using this approach,usually have much weaker grating lobes than the traditional FSS.Furthermore,their frequency response can be well predicted through the properties of their member element FSS.A prediction method for estimating the degree of expected grating lobe energy loss in designing multi-band FSS using this approach is provided.
通过对三缝隙实测与多层快速多极子算法(MLFMA,Multilevel Fast Multipole Algorithm)计算曲线进行对比,证明开发的程序可用于飞行器表面不连续特征研究。采用数值方法研究了单缝隙随宽度、单台阶随高度变化的规律,分析了三缝隙板、三台阶板电磁散射与其间距、极化方式之间的变化关系,并将散射结果与金属平板结果进行比较,定量总结了各参数的影响;数值结果表明,随着缝隙宽度、台阶高度的增加,不连续特征散射增强;三缝隙、三台阶的散射具有相互干涉性,且随间距的增加,曲线振荡增强。该结论可以用来提高飞行器的隐身性能。
