本文選題：粗糙面　切入點(diǎn)：后向增強(qiáng)　出處：《西安電子科技大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：后向增強(qiáng)現(xiàn)象是粗糙面電磁散射中非常重要的特性,它是指非相干散射分量在后向散射方向上出現(xiàn)峰值的現(xiàn)象,后向增強(qiáng)現(xiàn)象蘊(yùn)含目標(biāo)以及背景方面的很多信息,在微波,紅外以及可見光遙感和雷達(dá)目標(biāo)探測(cè)領(lǐng)域均有著重要的應(yīng)用。由于光頻段金屬的介電特性呈現(xiàn)特殊性質(zhì),即相對(duì)介電常數(shù)為復(fù)數(shù),且實(shí)部為負(fù),實(shí)部的絕對(duì)值遠(yuǎn)大于虛部,因此研究光波段金屬粗糙面的散射特性有著重要意義。本文主要圍繞大粗糙度粗糙面和微粗糙金屬粗糙面光散射的后向增強(qiáng)效應(yīng)展開討論。本文首先介紹了適用于大粗糙度粗糙面電磁散射的二階基爾霍夫近似理論,并給出了考慮遮蔽效應(yīng)的一階、二階基爾霍夫近似下非相干散射的散射截面表達(dá)式,分別計(jì)算和比較了光波段下金屬粗糙面和介質(zhì)粗糙面的非相干散射散射截面的角分布。論證了大粗糙度粗糙面光散射的后向增強(qiáng)效應(yīng)是由于電磁波在粗糙面之間的多次散射造成的。本文重點(diǎn)研究微粗糙金屬粗糙面光散射的后向增強(qiáng)效應(yīng)。首先,論述了微粗糙金屬粗糙面光散射后向增強(qiáng)效應(yīng)的物理機(jī)制——表面等離子體激元(SPPs)機(jī)制,并給出了SPPs的色散關(guān)系。利用退化的瑞利方程和微擾方法分別計(jì)算了光波段下一維高斯譜、矩形譜金屬粗糙面和二維高斯譜、圓柱譜金屬粗糙面的非相干散射的平均微分反射系數(shù)的角分布。計(jì)算結(jié)果表明只有當(dāng)入射光是TM極化時(shí)一維微粗糙金屬表面才會(huì)激發(fā)SPPs,造成非相干散射平均微分反射系數(shù)的后向增強(qiáng),而光入射到二維微粗糙金屬表面時(shí),四種極化方式都會(huì)出現(xiàn)不同程度的后向增強(qiáng)。同時(shí)分析了入射角、粗糙面粗糙度和粗糙面介電常數(shù)等對(duì)后向增強(qiáng)的影響。最后,本文研究了金屬薄層和理想導(dǎo)體涂覆介質(zhì)薄層表面光散射的特性,除了后向的增強(qiáng)還會(huì)存在“伴峰”現(xiàn)象,利用色散關(guān)系求解了薄層中導(dǎo)波的波數(shù)與薄層厚度的關(guān)系,并給出了散射角分布“伴峰”的位置與導(dǎo)波波數(shù)的關(guān)系。利用分層結(jié)構(gòu)中電磁散射的微擾理論分別計(jì)算了金屬薄層和理想導(dǎo)體涂覆介質(zhì)薄層表面光散射的平均微分反射系數(shù)的角分布。重點(diǎn)討論了薄層厚度對(duì)“伴峰”位置以及“伴峰”強(qiáng)度的影響,分析了入射角、薄層厚度以及介質(zhì)薄層介電常數(shù)等對(duì)后向增強(qiáng)的影響。
[Abstract]:Backward enhancement is a very important characteristic of electromagnetic scattering from rough surface. It refers to the phenomenon that the incoherent scattering component has peak value in the direction of backscattering. The phenomenon of backward enhancement contains a lot of information about the target and background. Infrared, visible remote sensing and radar target detection have important applications. Because of the special dielectric properties of metals in the optical band, that is, the relative dielectric constant is complex, and the real part is negative, the absolute value of the real part is much larger than that of the imaginary part. Therefore, it is of great significance to study the scattering characteristics of metal rough surfaces in light wave region. This paper mainly discusses the backward enhancement effect of light scattering from large roughness rough surfaces and micro-rough metal rough surfaces. The Second-Order Kirchhoff approximation Theory of electromagnetic scattering on rough Surface with large Roughness. The first order, second order Kirchhoff approximation is also given for the expression of the scattering cross section of incoherent scattering in the first order and the second order Kirchhoff approximation. The angular distributions of incoherent scattering cross sections of metal rough surface and medium rough surface are calculated and compared, respectively. It is proved that the backstepping effect of light scattering from large roughness rough surface is due to the electromagnetic wave between rough surfaces. In this paper, we focus on the backward enhancement effect of light scattering from micro-rough metal rough surfaces. In this paper, the physical mechanism of backscattering enhancement effect of light scattering from rough surface of micro-rough metal, surface plasmon excitation (SPPs) mechanism, is discussed. The dispersion relation of SPPs is given. Using the degenerate Rayleigh equation and perturbation method, the one-dimensional Gao Si spectrum, the rectangular spectrum, the metal rough surface and the two-dimensional Gao Si spectrum are calculated, respectively. Angular distribution of the average differential reflection coefficient of incoherent scattering from a cylindrical spectrum metal rough surface. The calculated results show that only when the incident light is TM polarized can the SPPs be excited on the surface of the one-dimensional micro-rough metal, resulting in the average differential of incoherent scattering. Backward enhancement of the reflection coefficient, However, when the light is incident to the two-dimensional micro-rough metal surface, the four polarization modes will show different degrees of backward enhancement. At the same time, the influence of incident angle, roughness of rough surface and permittivity of rough surface on the backward enhancement is analyzed. In this paper, the surface light scattering characteristics of metal thin layer and ideal conductor coated dielectric thin layer are studied. In addition to the backward enhancement, the phenomenon of "accompanying peak" also exists. The relationship between the number of guided waves and the thickness of the thin layer is solved by using the dispersion relation. The relationship between the position of the scattering angle distribution "accompanying peak" and the guided wave number is also given. The average micro-scattering on the surface of metal thin layer and ideal conductor coated dielectric thin layer is calculated by using the perturbation theory of electromagnetic scattering in stratified structure. The influence of the thickness of thin layer on the position and intensity of the "companion peak" is discussed. The effects of incident angle, thickness of thin layer and dielectric constant of dielectric thin layer on backward enhancement are analyzed.
【學(xué)位授予單位】：西安電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TN011

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相關(guān)期刊論文 前3條

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本文編號(hào)：1582665