共查询到19条相似文献,搜索用时 62 毫秒
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当电磁波的传输轴和各向异性超常介质的光轴成任意夹角时,发现在界面处可以产生反常全向全反射和反常负折射现象.导出了电磁波的入射角和能流折射角之间的函数关系,根据此关系可方便地选择合适的介电张量和磁导率张量,使特定入射角所对应的折射是正或是负.此外,发现当入射角小于某一角度时,尤其在垂直入射附近时,透射率最小甚至为零;基于这一特性,提出了一种新型的薄片型高通空间滤波器的构想,和传统的空间滤波系统相比,可以大大减少滤波系统的体积;这一特性也可用于构造空间低频反射器件.
关键词:
超常介质
各向异性
反常传播
空间滤波 相似文献
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研究中通过建立和求解填充各向异性超常媒质的矩形波导TE模式和TM模式的波动方程和场分布方程,讨论了各向异性超常媒质矩形波导的有效介电常数、有效磁导率、相位常数以及传输系数与所填充超常媒质本构参数之间的变化关系.研究发现,填充了各向异性超常媒质的矩形波导的导波特性在截止频率之上的频率区域,其导波特性由所填充超常媒质的横向本构参数决定,而与超常媒质的纵向本构参数无关.但是,在截止频率之下的频率区域,该矩形波导的导波特性则由所填充超常媒质的横向本构参数和纵向本构参数共同决定.研究中通过典型的计算实例对所得到的结
关键词:
各向异性
超常媒质
矩形波导
导波特性 相似文献
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研究了完全各向异性超常材料中的倒退波传播现象,得到了在材料本征轴和传输轴成任意角度情形下倒退波形成的条件,分析了超常材料的介电张量和磁导率张量、电磁波的偏振方式对倒退波形成和传播的影响. 在此基础上,进一步分析了几种不同色散曲线关系的各向异性超常材料中倒退波的产生情况,获得了电磁波波矢和坡印亭矢量(能流)夹角的具体表达式和倒退波传播的一般性结论. 此外,还研究了近零介电常数超常材料中倒退波的传播特性,发现在此类超常材料中倒退波只能是完美倒退波.
关键词:
超常材料
负折射
倒退波
各向异性 相似文献
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提出了一种利用含有负介电常量和磁导率张量的各向异性超常材料实现偏振分离的方法。通过分析电磁波在无损耗各向异性超常材料中的传输性质以及透射率与入射角度的关系,分类比较了由不同符号的介电常量和磁导率张量组合而成具有不同波矢面的各向异性超常材料的偏振分离特性,比较结果表明波矢面为单叶双曲面和椭球双叶双曲面的各向异性超常材料的偏振分离特性强。前者可以实现入射波中的s分量和p分量中某一分量正折射,另一分量负折射,且在一定条件下可以同时全透射,从而实现大角度偏振分离。后者在一定条件下可实现入射波中的s分量和p分量某一分量全反射,另一分量全透射,从而实现偏振分离。最后,对从各向同性介质入射到这两种各向异性超常材料中的高斯光波的传输进行了模拟计算,结果表明这两种各向异性超常材料可以实现很好的偏振分离功能,有潜力成为新型的偏振分离元件。 相似文献
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根据矩阵Padé逼近理论,把磁化色散介质的相对磁导率张量表示成以jω为自变量的矩阵函数形式,用/t代替jω后过渡到时域,再引入离散时域移位算子代替时间微分算子.进而导出磁化色散介质中的磁感应强度B和磁场强度H在离散时域的色散关系,并将其具体应用于旋磁介质,得到了这种磁化色散介质的Padé时域有限差分方法的递推表达式.作为验证,用这种方法计算了磁化铁氧体球的后向雷达散射截面,所得结果与文献结果一致.理论推导及算例表明,该方法是正确和有效的.
关键词:
各向异性介质
色散介质
矩阵Padé逼近
时域有限差分方法 相似文献
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以填充各向异性超常媒质矩形波导中的电磁场解为基础,通过建立与求解填充各向异性超常媒质交错结构的矩形谐振腔的谐振方程,深入研究了三维各向异性超常媒质交错结构的亚波长谐振特性.结果发现,三维各向异性超常媒质交错结构的亚波长谐振条件具有更为多样性的物理解,在固定参数下,其物理解的个数往往超过一个,还针对谐振结构的横向尺寸对亚波长谐振条件的影响进行了讨论.结果表明,随着横向尺寸的减小亚波长谐振条件的物理解数量将逐渐增多直至趋于无穷.这意味着即使超常媒质的本构参数无法控制,仍然可以通过调节谐振结构的横向尺寸来得到亚波长谐振腔.
关键词:
各向异性
超常媒质
交错结构
亚波长谐振 相似文献
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使用时域有限差分法,研究了各向异性特异材料(AMM)作为包层的AMM/介质/AMM波导中表面等离子体的共振性质.色散关系表明,当特异材料为负磁导率的always-cutoff型时,AMM/介质/AMM波导支持TE极化的表面等离子体,表面等离子体的波长随着中间介质层的厚度和特异材料磁等离子体频率的减小而变短.在有限长度AMM/介质/AMM波导中,由于两端界面的反射,表面等离子体模在波导中形成Fabry-Perot共振,而实现亚波长的表面等离子体微腔.在共振频率,电场强度在微腔的中部达到最大值,而磁场分别在两端界面处达到最大,电磁能强局域在中间介质层中,这一性质将在可调的具有强局域特性的亚波长微腔及腔量子电动力学中具有潜在的应用. 相似文献
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We construct a prism-waveguide system with electro-optical (EO) crystal and biaxially anisotropic metamaterial (BAM) as the prism and guiding layer, respectively. Stationary-phase approach is employed to explore the modulation of EO material on the phase, reflectivity and lateral shift, different thicknesses of air and BAM are also considered. Simulation results show that the refractive index change of EO material does not change the maximum value of lateral shift and a configuration with larger phase maximum value, smaller reflectivity minimum and sharper angle-reflectivity curve generates a larger value of absolute value of lateral shift. These results give us a guidance for the design of EO-modulated sensors based on tunable lateral shift. 相似文献
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We present a theoretical study of the propagation properties of polarized photons passing through the cavity with an anisotropic metamaterial. We find that the resonant peaks of transmission appear for photons polarized in a certain direction corresponding to a negative element of the permittivity tensor. This indicates the potential for applying such cavity structures as filters for photons with certain polarizations. The resonant peak of transmission for photons having a given frequency can be achieved by adjusting the thicknesses of the air and metamaterial. If the frequency of the incident photons and the thickness of the metamaterial are fixed, the cavity structure can be used as a photon switch controlled by the thickness of the air. The effect of the absorption is considered, and the result shows that the transmission peak always appears, even for metamaterials with large absorption. Finally, the polarization manipulation of such structures is explored. 相似文献
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Anisotropic metamaterial with only one component of the mass density tensor near zero(ADNZ) is proposed to control the sound wave propagation. We find that such an anisotropic metamaterial can be used to realize perfect bending waveguides. According to a coordinate transformation, the surface waves on the input and output interfaces of the ADNZ metamaterial induces the sound energy flow to be redistributed and match smoothly with the propagating modes inside the metamaterial waveguide. According to the theory of bending waveguide, we realize the "T"-type sound shunting and convergence, as well as acoustic channel selection by embedding small-sized defects. Numerical calculations are performed to confirm the above effects. 相似文献
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The research of high-directive anisotropic magnetic metamaterial antenna loaded with frequency-selective surface 下载免费PDF全文
This paper uses a Computer Simulation Technology microwave studio to
simulate the performance of a new high-directivity anisotropic
magnetic metamaterial antenna loaded with a frequency-selective
surface. Frequency-selective surface with cross-dipole element has a
great effect on the directivity, radiation pattern, and gain of such
an antenna. The experimental results show that frequency-selective
surface (FSS) significantly improve the radiation performance of
anisotropic magnetic metamaterial antenna. For example, as a single
anisotropic magnetic metamaterial antenna, half power beam width is
4 degrees in the H planes, and the gain of this antenna is 19.5 dBi at
10 GHz, achieving a 2.1 degree increment in half power beam width,
and a 7.3 dB gain increment by loading with the FSS reflector. The
simulating results are consistent with our experimental results. 相似文献
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Magnetization relaxation of uniaxial anisotropic ferromagnetic particles with linear reaction dynamics driven by DC/AC magnetic field 下载免费PDF全文
《中国物理 B》2021,30(9):90202-090202
The response of uniaxial anisotropic ferromagnetic particles with linear reaction dynamics subjected to alternating current(AC) or direct current(DC) bias magnetic field is evaluated by the reaction–diffusion equation for the probability distribution function of the molecular concentration in the spherical coordinate system. The magnetization function and the probability distribution function of the magnetic particles in the reaction system are derived by using the Legendre polynomials and Laplace transform. We discuss the characteristics of magnetization and probability distribution of the magnetic particles with different anisotropic parameters driven by a DC and AC magnetic fields, respectively. It is shown that both the magnetization and the probability distribution decrease with time increasing due to the reaction process. The uniformity of the probability distribution and the amplitude of the magnetization are both affected by the anisotropic parameters.Meanwhile, the difference between the case with linear reaction dynamics and the non-reaction case is discussed. 相似文献