中文摘要：

基于斜切45°规则进口直腔进气道,设计了5mm×5mm格栅、15mm×15mm格栅、进口开放和封闭4种模型。结合多层快速多极子方法（Multilevel fast multipole method,MLFMM）对格栅电磁散射特性进行仿真研究,并制作了相同的试验模型进行验证,获得了格栅特征几何参数,如格栅孔间距、格栅倾角以及格栅厚度等对电磁散射特性的影响。研究表明：（1）格栅电磁散射特性数值计算结果在角域-30°~30°范围内与试验结果比较吻合,验证了仿真计算的有效性;（2）10GHz下,格栅孔间距为λ/2时,格栅电磁屏蔽效率约为43%,而孔间距达到λ/6时,接近于完全屏蔽;（3）随着格栅倾角增大,格栅电磁屏蔽效果逐渐减弱;（4）随着格栅厚度增加,格栅电磁屏蔽效率增加,但增加的幅度逐渐减小。

英文摘要：

Based on the oblique import inlet of 45° coupling with straight cavity, four inlets with intake open and close coupling 5 minx 5 mm grille and 15 min× 15 mm grille are designed. The numerical simulation is carried out on electromagnetic scattering characteristics of grille based on multilevel fast multi- pole method （MLFMM）. And then the same inlet test models are made to verify the method for electro- magnetic scattering calculation. Finally, the typical geometric parameters of electromagnetic scattering characteristics such as the grille hole spacing, grille inclination angle, and grille thickness are obtained. Results indicate that： （1）The calculated result of electromagnetic scattering characteristics of grille is close to the experimental data at the azimuth angle from --30° to 30°, indicating the validity of numeri- cal simulation method. （2） At the frequency of 10 GHz, the electromagnetic shielding effectiveness can reach about 43% when the grille hole spacing is λ/2（λ represents wavelength）, and it will be shielding entirely while the grille hole spacing achieves λ/6. （3） With the increasing of the grille inclination angle, the electromagnetic shielding effectiveness reduces gradually. （4）With the increasing of the grille thickness increasing, the electromagnetic shielding effectiveness also increases gradually, but the increasing extent decreases.