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偏振遥感识别低反射率伪装网研究 总被引:2,自引:0,他引:2
偏振遥感是一种新型的侦察手段,具有传统遥感所不具备的优点,是研究大气与地面目标的重要方法.为了研究伪装目标的偏振散射特征,在光学与红外波段测量了三色迷彩伪装网的偏振参数.研究发现,在探测条件一定的情况下,伪装网散射光的偏振度受入射角度和表面反射率的影响较大.入射角增大,伪装网散射光的偏振度也随之增大;表面反射提高,其散射光的偏振度降低.偏振度成像可以增强低反射区域的亮度和对比度,而偏振角成像对伪装网的外形特征非常敏感,偏振遥感对复杂背景中的低反射率伪装目标识别具有独特优势,对军事伪装目标的生存构成了严重威胁. 相似文献
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在晴朗无风的白天及夜间考察了不同发射率伪装网装饰布(热红外发射率从0.63~0.94)与樟树树冠的辐射温差,并参照可见光变形迷彩设计理论分析了林地型伪装网中间色斑块的发射率取值范围。实验表明,传统林地型伪装网在热红外波段不能满足昼夜与林地背景融合的要求。林地型伪装网要满足强日照下热红外伪装的要求,中间色斑块的发射率必须小于0.63;要满足夜间热红外伪装的要求,中间色斑块的发射率不小于0.83。综合采用发射率可变涂料、降低太阳能吸收率、增强网面对流换热等技术手段可改善林地型伪装网与背景的昼夜兼容能力。 相似文献
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Improvement on the wave absorbing property of a lossy frequency selective surface absorber using a magnetic substrate
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An equivalent-circuit model is used to analyse the improvement of the wave absorbing performance of the lossy frequency selective surface(FSS) absorber by using a magnetic substrate,showing that it is possible to widen the wave absorbing bandwidth.Three pieces of magnetic substrates are prepared.According to the complex permittivity and permeability,the reflectivity of the corresponding absorber is calculated by the finite difference time-domain(FDTD) method,and the bandwidth of the reflectivity below 10 dB is optimized by genetic algorithm.The calculated results indicate that the wave absorbing performance is significantly improved by increasing the complex permeability of the substrate;the reflectivity bandwidth below 10 dB of the single layer FSS absorber can reach 3.6-18 GHz with a thickness of 5 mm,which is wider than that with a dielectric substrate.The density of the FSS absorber is only 0.92 g/cm 3.Additionally,the absorption band can be further widened by inserting a second lossy FSS.Finally,a double layer lossy FSS absorber with a magnetic substrate is fabricated based on the design result.The experimental result is consistent with the design one. 相似文献
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设计了一种基于超材料的吸波材料,吸波材料由周期性排列的电阻片,基体以及金属背底构成. 采用时域有限差分法(FDTD)计算了吸波材料的反射率,并用遗传算法优化了吸波材料的吸波带宽,得到一种反射率在8-18 GHz小于-10 dB的吸波材料,材料厚度仅为3 mm. 采用手糊工艺制备了空心石英纤维增强环氧树脂基体,丝网印刷制备了电阻片,实现了所设计的吸波材料,测试表明,实验结果和设计结果一致.
关键词:
雷达吸波材料
超材料
频率选择表面
遗传算法 相似文献
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