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频率选择超材料是隐身雷达罩的理想罩体材料,内部存在大量周期性金属超结构单元,常规雷电屏蔽方法无法对其形成有效保护。该文利用环氧树脂基材制备一种频率选择超材料,研究雷电冲击电压下这种超材料表面的放电通道形貌特征,提出夹角因子参数并测量了50%沿面放电电压。在此基础上,利用夹角因子对超材料表面绝缘特性进行评估,得出沿面放电电压随偏离角变化的规律。结果表明,超材料表面放电通道呈折线型,由两类放电路径组成:第一类路径与超结构周期方向平行,第二类路径与超结构周期方向夹角45°。进一步分析发现,超材料沿面放电的主通道发生在沿绝缘间隙总长度最短的路径上。随着双电极连线偏离超结构周期方向角度的增大,沿面放电电压先增后减,当偏离角为0°或45°时,放电电压较低;当偏离角为22.5°时,放电电压较高。研究结果可为超材料隐身雷达罩的雷电防护提供参考。
Frequency-selective metamaterials are the ideal cover material for stealth radomes. There are a large number of periodic metallic superabsorbent units inside, which can not be effectively protected by conventional lightning shielding methods. In this paper, a kind of frequency-selective metamaterials was prepared by epoxy resin substrate. The morphology of the discharge channels on the surface of such metamaterials under lightning impulse voltage was studied. The included angle factor parameters were measured and the 50% creeping discharge voltage was measured. On this basis, the surface insulation characteristics of metamaterials are evaluated by the included angle factor, and the law of variation of creeping discharge voltage with deviation angle is obtained. The results show that the surface discharge channels of metamaterials are of a polygonal shape and consist of two types of discharge paths: the first one is parallel to the periodic direction of the superstructure and the second one is 45 ° with the periodic direction of the superstructure. Further analysis revealed that the main channel of metamaterial creeping discharge occurred along the shortest path along the insulation gap. The discharge voltage increases first and then decreases with the increase of the angle of the double electrode connection away from the superstructure cycle direction. When the deviation angle is 0 ° or 45 °, the discharge voltage is lower. When the deviation angle is 22.5 °, the discharge voltage Higher. The results can provide reference for thunder and lightning protection of metamaterial stealth radome.