Study of Metamaterial Configuration and its Applications for Frequency Selective Shielding Screen and Radome

讨论了有限长金属棒阵列片作为超材料或人工设计材料的电磁特性，并研究了其主要用途，频率选择屏蔽屏和天线罩材料。金属棒周期性地排列在薄的电介质片上。棒的共振发生在特定频率，其波长约等于棒长度的两倍。金属棒阵列片的介电常数ε_r=ε_r′-jε_r”，是假定片为均匀时的平均介电常数，在金属棒谐振下表现为频散。在低于谐振频率时，由于金属棒的极化，f_0,ε_r'变高。介电常数在f_0处迅速减小，当频率高于谐振频率时，ε_r′变为负值。虚部ε_r '在f_0处达到最大值。作为磁性材料，我们考虑了磁性金属微粒的杂化材料，实验证实了它们的介电常数几乎为零。金属棒对准板的透射系数在f_0处最小。频率选择性电磁波屏是由两个或多个金属棒排列的薄片和它们之间的间隔材料制成的。实验证实了它们的屏蔽性能。作为该材料的另一种应用，本文讨论了吸收剂。作为吸波材料，金属取向片材的关键特性之一是ε_r'在f_0附近迅速减小，从而导致片材输入阻抗的电抗X发生相反的频率变化，即dX/dw< 0。在常规材料中，X的频率特性总是dX/dw> 0，这就是福斯特电抗定理。由于金属棒对准片和常规介质片的频率变化是相反的，因此当这些片层叠时，可以使输入阻抗的频率变化最小化。基于这一思想，实现了宽带吸收器。频率选择屏蔽屏幕和宽带吸收器，都是由棒对齐片，现在正在进入使用的过程中。少

The electromagnetic properties of finite-length metal-rod array sheets are discussed as metamaterial, or artificially designed material, and as their chief uses, frequency selective shielding screen and radome materials are investigated.The metal rods are periodically aligned on a thin dielectric sheets. The resonance of the rods occurs at specific frequency whose wave-length is approximately equal to double the rod length. The metal-rod array sheet permittivity,ε_r=ε_r'-jε_r", which is a average permittivity when the sheet is supposed to be homogeneous, shows frequency dispersion by the metal rod resonance. At frequencies lower than the resonant frequency, f_0,ε_r' becomes high due to the polarizations of the metal rods. The permittivity decreases rapidly at f_0, and at frequencies higher than the resonant frequency, ε_r' becomes negative. The imaginary part, ε_r", becomes maximum at f_0. As magnetic materials, hybrid materials of fine particles of magnetic metals are considered, and … More experimentally their permittivity was confirmed to be almost zero.The transmission coefficient of the metal-rod aligned sheet becomes minimum at f_0. The frequency selective EM wave screens are made with two or more metal-rod aligned sheets with spacing materials between them. Their shielding properties are experimentally confirmed.As one of the another applications of this material, absorber is discussed. As absorbing material, one of the key properties of the metal aligned sheet is the rapid decrease of ε_r' around f_0, which leads to the opposite frequency change in reactance X of the sheet input impedance, that is, dX/dw< 0. In conventional material, the frequency property of X is always dX/dw> 0, which is known as Foster's reactance theorem. Since the frequency changes of the metal rod aligned sheet and conventional dielectric sheet are opposite each other, it is possible to minimize the frequency change of input impedance, when these sheets are laminated. Based on this idea, the wide band absorber is achieved.The frequency selective shielding screens and the wide band absorbers, both made of the rod aligned sheet, are now in process of coming into use.. Less