教授说，这个天线是个 点状的发射天线！周围都用金属板围起来了（是不是金属板不记得了，反正是被围起来了）。然后 在近场里放些如图的对称的金属线（布局和线的多少，试验着来），目的是让 信号 如图，产生 聚拢不发散～！
泪求高手请教，如何操作，希望您能留几句话，必能帮助到我。如能发给小妹一个做好的半成品，成品再感激不过了～（有偿相托，有意的高手可以EMAIL我）！
万谢！ weitao_1011@163.com
Since it was first proposed to use subwavelength apertures to obtain resolutions beyond the diffraction limit (
1), the electromagnetic near field has enjoyed continued scientific interest. Much of the current attention stems from the work showing that a negative refractive index slab behaves as a perfect lens by focusingboth the near- and far-field components emanating from a source (
2). Following this work, negative refractive index and negative permittivity (
3–
6) superlenses have been experimentally verified at microwave, infrared, and optical frequencies. Recently, a related but alternative approach was introduced, which relies on patterned, grating-like surfaces, to obtain subwavelength resolutions (
7,
8). These surfaces, referred to as near-fieldplates, can be implemented at arbitrary frequencies. We now present a microwave implementation of this approach.
A near-fieldplate is a subwavelength-structured device that acts as a modulated, nonperiodic surface reactance (it consists of only inductive and capacitive elements). The surface reactance is designed to set up a highly oscillatory electromagnetic field that converges at a prescribed focus in the near field. Depending on their design, near-fieldplates can focus the field of a plane wave (
8) or, as shown here, a finite source. Further, they can be tailored to produce focal patterns of various symmetries and shapes. As compared withslabs withnegative material parameters, near-fieldplates only require single-layer processing. The plate reported here was fabricated through standard photolithographic methods.
Given that near-fieldplates provide strong spatial confinement of electromagnetic waves, they hold promise for near-fieldsensor and microscopy applications, as well as nonradiative wireless power transference (
9) and beam-shaping millimeter-wave and optical devices. Methods for confining electromagnetic energy to subwavelength dimensions have been extensively studied in near-fieldmicroscopy (
10–
12). In particular, near-fieldprobes such as tapered waveguide apertures and metallic and dielectric tips have been used (
13). Near-fieldplates offer some distinct advantages over these methods. Unlike conventional probes, the spatial spectrum of the focus can be easily manipulated, because it is determined by the plate's patternedsurface. Moreover, near-fieldplates offer a larger operating distance (a depth of focus) (
7). The extended spatial spectrum provided by standard near-fieldprobes is only available very close to the small tip or aperture, as a result of the strong divergence of the radiation. In contrast, near-fieldplates expand the region of the extended spatial spectrum to a length scale, which is, in practice, comparable to that of the resolution. Finally, we note that, similar to slabs withnegative material parameters and metallic tips, near-fieldplates can resonantly amplify the field at the plate's surface and therefore at its focal plane (
8).
There are four basic steps to design a near-fieldplate (
8). The first step is to use back-propagation to find the field at the surface of the plate (aperture field) that produces the desired focal pattern. Back-propagation consists of phase-reversing the propagating spectrum and restoring the evanescent spectrum (
7,
8). The second step involves finding the current density on the plate needed to produce the desired aperture field, which is computed by solving an integral equation representing the boundary condition at the plate's surface (
8the field profile (4)which has a null-to-null beamwidth of
Fig. 1.
Schematic showing the experimental setup. The figure shows the coaxially fed dipole antenna (cylindrical source) and near-fieldplate inside a parallel-plate waveguide. The top ground plane has been removed for clarity. The near-fieldplate consists of an array of interdigitated capacitors printed on an electrically thin microwave substrate. Also shown is a contour plot of the simulated electric field on the image side (logarithmic scale). The dashed white line denotes the focal plane. The three central elements of the near-fieldplate are shown in the inset; Hc= 15.0 mm, Wc). Next, the required surface impedance of the plate is found by taking the ratio of the aperture field to the current density. Lastly, a physical implementation of the surface impedance is realized. This final step requires careful design consideration and the proper choice of material parameters, appropriate to the frequency of operation.
The experimental setup (Fig. 1) results in a field that is two dimensional (2D). In our geometry, the electric field depends on the coordinates y(parallel to the plate) and z(normal to the plate) but does not vary in the xdirection (the direction of field polarization, parallel to the antenna). In (
7), it was shown that an aperture field of the form (1)can focus in the near field, where f(y, z= 0) is the aperture field, M(y) is a function that has one or more poles withnonzero components in the spatial complex plane, iis the imaginary unit, and q0is a constant related to the resolution Δythrough (2)In the case where M(y) has a single pole, its imaginary component defines the focal length. The aperture field we consider here is given by the following expression (3)This aperture field was shown in (
8) to produce a focus at a distance z= Lfrom the plate, with= 7.5 mm.
A passive near-fieldplate was then designed to produce the aperture field of Eq. 4. Specifically, the designed near-fieldplate focuses the field emanating from s-polarized, electric field components Ey= Ez= 0, cylindrical source (the dipole antenna in
Fig. 1) oscillating at 1.027 GHz to a subwavelength focus witha full width at half maximum (FWHM) of λ/18. This value should be compared withλ/2.78 for the diffraction-limited case. The positions of the focal plane and antenna were both chosen to be at a distance of L= λ/15 from the near-fieldplate, as shown in
Fig. 1. The near-fieldplate was designed to operate in a parallel-plate waveguide environment (a 2D scattering chamber). In accordance withimage theory, the top and bottom ground planes act as mirrors and make the finite-height near-fieldplate and the source appear as though they were infinite in the xdirection. The microwave source used in the experiments was a coaxially fed thin wire dipole antenna, which acted as a vertical line current. The outer conductor of the coaxial feed was attached to the bottom ground plane, whereas the center conductor, which acted as the dipole antenna, was attached to the top ground plane. The width of the near-fieldplate, in the ydirection, was chosen to be roughly one free-space wavelength: W= 292.2 mm.
The current density on the near-fieldplate was obtained from the aperture field Eap(Eq. 3), by numerically evaluating the integral equation (
14) (5)which represents the boundary condition at the surface of the near-fieldplate (
8). Here, η0= 120π ohms is the wave impedance of free space, k0= 2π/λ, Jxis the current density on the plate, M0is an amplification factor, and Einc(y) is the electric field incident on the near-fieldplate from the antenna (6)where Ixis the current amplitude of the antenna and H0(2)is the zeroth-order Hankel function of the second kind (a time-harmonic progression of eiωtis assumed, where ω is the radial frequency and tis the time). The desired surface impedance, ηsheet, was found by taking the ratio of the aperture field to the current density: ηsheet(y)= Eap(y)/Jx(y).
For this particular near-fieldplate design, the amplification factor was set to M0= 2 and q0= 10k0to yield a resolution of ≈ λ/20. To emulate a continuously varying surface impedance, we discretized the plate into n= 39 separate elements of width Wc≈ λ/40 and height Hc≈ λ/20 (
Fig. 1). We determined the impedance of each element (Zsheet) using the properly normalized surface impedance (ηsheet) evaluated at the center of each strip from Eq. 5: . The impedance elements found through this procedure are all capacitive (
15). This was expected, given that the mutual impedance matrix defining the electromagnetic interaction between the impedance elements is predominantly inductive for s-polarized radiation. These inductive mutual impedances resonate withthe capacitive impedances Zsheetand result in an aperture field that is M0= 2 times higher in amplitude than the field incident on the plate.
The near-fieldplate was implemented as an array of interdigitated copper capacitors printed on an electrically thin microwave substrate, as shown in
Fig. 1(
15). The operating frequency of the fabricated near-fieldplate was 1.027 GHz, which was 2.7% higher than the design frequency of 1.0 GHz. This frequency difference is consistent withetching tolerances associated withthe fabrication of the near-fieldplate, as well as withvariations in the parallel-plate waveguide height in which it was tested.
Figure 2, A and B, shows contour plots of the experimental and calculated electric field at the operating (1.027 GHz) and design (1.0 GHz) frequencies, respectively. The electric field amplitude has been normalized to its largest value at a given z. The plots show very good agreement between the measurements and finite element computations, which took into account all electromagnetic interactions as well as the losses associated withthe finite conductivity of the capacitors. The relative magnitude of the electric field contour is the same for both plots, and the minima and maxima of the highly oscillatory field between the plate and focal plane show very good agreement between the simulation and the experiment.
Figure 2Ccompares the simulated and measured electric field intensity along the focal plane, located roughly at λ/15 (2.0 cm) from the near-fieldplate. The main peaks in the two plots exhibit a FWHM of λ/18. Fourier transforming the experimental focus reveals that it is composed of spatial frequencies in the range –10k0y0. To emphasize the narrowness of the focus, we plotted an additional curve illustrating what the beamwidth of the electric field would be if the near-fieldplate were not present. The resolution (FWHM of the focus) was found to decrease from its best value of λ/20.0 at 1.025 GHz to λ/9.3 at 1.065 GHz (
15). At frequencies below 1.025 GHz, the focal pattern exhibited multiple peaks.
[/url]Fig. 2.
Normalized plots of the electric field (image side). Contour plot of the experimental (A) and simulated (B) electric field amplitude. The focal planes are denoted by the dashed white lines. (C) Normalized intensity along the focal plane of the near-fieldplate. The red curve shows the electric field resulting from the coaxially fed antenna in the absence of the near-fieldplate.
This work demonstrates the feasibility of implementing passive surfacesthat can focus microwave electromagnetic energy to extreme subwavelength dimensions. At infrared and visible light frequencies, such structures could be implemented withplasmonic (inductive) and dielectric (capacitive) materials ([url=http://www.sciencemag.org/content/320/5875/511.full?sid=f64d3bf7-2eea-44a9-8d4e-cc224b8e3eac#ref-16]16).
看着像是从论文里截取的图片，不妨直接把论文上传上来？资料越多，得到的帮助可能就越多，甚至有可能在某种交集中真的能得到你想要的东西。
1. 没用过CST 2010，请先阅读CST文档《CST STUDIO SUITE - Getting Started》和《CST MICROWAVE STUDIO - Work Flow and Solver Overview》。
2. 描述你的仿真任务的时候请注意描述的准确性，“目的是让 信号 如图，产生 聚拢不发散～！”，请问这是正常的能理解的汉语吗？
“周围都用金属板围起来了（是不是金属板不记得了，反正是被围起来了）”，到底“是金属”还是“不是金属”？
“在近场里放些如图的对称的金属线（布局和线的多少，试验着来）”，要怎么试验？不同的长度？不同的宽度？不同的高度？
没有任何参数值，没有任何specification：
线是什么材料？什么尺寸？
基板什么材料？什么尺寸？
“地”是什么尺寸？
模型工作的频率范围？
“信号 如图，产生 聚拢不发散～”用什么参数衡量？
实测要如何进行？
3. 如何软件操作，请参考1。想要半成品，请仔细捉摸2。想有偿，不如先报个价，想挣钱的自然会联系你。
谢谢您的回复！题材的确出自一片科学杂志。已经贴上去了！前辈帮帮忙！
你好，hefang. 因为好多术语都不懂怎么讲，只是被老师告知是这样的！要求模拟出来。完全是要自学，我连怎么画出来图都不会！我已经将具体内容贴上来了！
希望您能帮帮忙！哪怕指点下怎么画出来。万谢
钦佩啊！刚去资料库看了下，全是你发的资源啊！你肯定是教授吧？求您帮帮忙啊！
既然是自学，那就真的需要自己学习了。
怎么在CST MWS里画图，2楼写的那两个文件解释得很详细。如果想自己画，那就只能自己看。
如果刚刚接触仿真，“知道怎么画”只不过是软件操作的层面，“知道为什么要这样画”才是你需要学习的。比如：
楼主能不能用最简单的两三句话描述这篇文章说的是什么？描述要简单但是要清楚，用词要准确。如果不理解文章说的是什么的话，仿真没办法做的。
文章中提到的频率范围是多少？
文章中的激励源是什么？
文章中的衍射在什么微波器件中观测的？
文章中通过哪个参数观测衍射现象？
文章中通过哪个参数观测“聚拢不发散”现象？
请楼主思考一下上面的问题，每一个问题都对应仿真模型中一个或多个参数的设置原则。
谢谢你～！时间紧迫啊！hefang神圣啊，能不能帮忙把范围缩小点？就一个月的时间啦！白天还要上班！
首先，我不是教授，不是神圣，不是工程师。
其次，先做小人，帮你做免谈，你的教授让你做不是让我做。也别提钱，提钱伤我感情……。
我觉得我已经替你把范围缩得挺小了，从一个看不懂的标题归纳到5个点已经足够小了吧。既然不想花时间思考，我替你回答：
文章描述在波导中使用平面的平行电容结构控制单极天线辐射的电磁场所产生的衍射现象。
设计频率为1.027 GHz。
因此CST MWS仿真模型的频率范围可以考虑0-2 GHz。（不考虑波导的截止频率）
同轴线馈电的dipole antenna。不过从描述看应该是monopole。
CST MWS中的模型可以把单极天线用同轴线结构建模，用波导端口做激励。
Parallel-plate waveguide。
CST MWS模型中可以完整建模这个波导，使用Electric边界，normal背景材料。也可以考虑不建波导外边缘，使用conducting wall边界，normal背景材料。
电场。
CST MWS模型中需要设置对应频率的电场监视器。
Full Width at Half Maximum。
如果仿真也要呈现这个的话，CST MWS中要设置postprocessing。
有上面的信息，就可以运行仿真了。楼主还是不想自己试试吗？
PT读书确实很累，我可以理解，不过对我来讲这不能成为找别人代做的借口。
评论专业～！谢谢您！看你资料在长春读过书，在英国读的博士。哈哈我吉林松原的～！
你肯定不差钱，这我知道。的确是我的想法不妥，很龌龊。我还是抓紧搞一下吧。再次感谢啊～！
Mr. Hefang 有没有什么入门的资料学习学习？ 你上面给的是 怎么用CTS吧？ 我搜索了在CTS资料库里面没有也！
那里可以下载啊？谢谢你啊 帮帮忙！
声明：网友回复良莠不齐，仅供参考。如需更专业系统地学习CST，可以购买资深专家讲授的CST最新视频培训课程。
