Enhanced millimeter wave transmission through quasioptical subwavelength perforated plates

In this paper, we show that the phenomenon of extraordinary transmission through arrays of subwavelength holes, present in the optical regime, is also present in the millimeter wave range. After presentation of the theoretical foundations of the enhanced transmission, measurements of the transmission response have been performed on different samples by using a millimeter wave quasioptical vector network analyzer in the range between 45 and 110 GHz. The prototypes have been fabricated in Aluminum plates with several thickness and different hole diameters drilled by using a laser machine. Good agreement between theory and experiment is obtained, with clear signals of the existence of resonant transmission at wavelengths close to the period of the array. Possible applications in frequency selective surfaces and near-field imaging are envisaged.     

Extraordinary transmission of light through an irregular system of holes in a metal film

It is experimentally shown that the near- and mid-IR transmission coefficient of a 17-nm silver layer sputtered onto a Lavsan film with an irregular system of small holes is 2–6 times higher than the transmission coefficient of the same layer on a nonperforated continuous Lavsan film. This effect is wideband. It is observed at wavelengths of 1500–5000 nm. The physical-optics calculation of transmission of light through the holes in a silver film that are identical to the holes in the Lavsan film is unable to explain this effect since the hole diameter (200 nm) is too small. The system microstructure is studied with the atomic-force and electron microscopes. A possible mechanism of the effect of extraordinary transmission of radiation is discussed.     

Electromagnetic transmission through mesh covered apertures and arrays of apertures in a conducting screen

The problem of electromagnetic transmission through wire mesh covered arbitrarily shaped aperture or arrays of apertures (possibly covered by a thin lossy dielectric sheet) in a perfectly conducting ground plane is considered. The equivalence principle and image theory are used to derive an integral equation for the equivalent magnetic currents. The method of moments is utilized to solve the integral equation, with the aperture modeled by triangular patches. Numerical results are presented for transmission coefficients and transmission cross-section patterns for electrically small apertures.     

PCB通孔镀铜添加剂

高厚径比小孔通孔电镀是PCB电镀铜的重要环节。文章将介绍一种在普通高酸低铜电镀液中加入一种吡咯与咪唑的含氮杂环聚合物的通孔电镀铜添加剂,经过通孔电镀和CVS实验结果,证明该电镀液对厚度与孔径比达到10:1的小孔(Φ=0.25 mm)的通孔电镀能力达到百分之八十五以上,具有很好的实用价值。     

Increase of the transmission in cut-off metallic hole arrays

In this letter, the phenomenon of extraordinary transmission through arrays of subwavelength holes in the microwave range is demonstrated. It is also shown that the magnitude of the transmission is strongly dependent on the number of holes in the sample. Prototypes have been designed and fabricated in an Al plate. The transmission response is measured with a millimeter wave quasi-optical vector network analyzer in the range between 40 and 70GHz. These measurements show a resonant total transmission at wavelengths close to the period of the array which depends strongly on the number of resonant holes. These results can give rise to interesting applications such as frequency selective surfaces and other quasi-optical structures.     

Enhanced electron emission from phosphorus-doped diamond-cladsilicon field emitter arrays

Undoped and phosphorus (P)-doped diamond-clad Si field emitter arrays have been successfully fabricated using microwave plasma chemical vapor deposition (MPCVD) technology. The electron emission from the blunt diamond-clad microtips are much higher than those for the pure Si tips with sharp curvature due to a lower work function. Furthermore, the characteristics of emission current against applied voltage for the P-doped diamond-clad tips show superior emission at lower field to the undoped ones. After the examination of Auger electron spectroscopy (AES) and electrical characteristics of as-grown diamond, such a significant enhancement of the electron emission from the P-doped diamond-clad tips is attributed to a higher electron conductivity and defect densities     

Single-mode lightwave transmission in SOI-type photonic-crystalline-defect waveguides with phase-shifted holes

Single-mode lightwave transmission was observed in novel line-defect photonic-crystal (PC) waveguides. The waveguide structure is constructed by adding phase-shifted holes in an ordinary missing-hole line defect. This device permits a fine single-mode lightwave transmission even though the waveguide structure is fabricated on silicon-on-insulator (SOI) substrate, which seriously promotes off-plane leakage of waveguiding modes     

Spin-dependent transmission of holes in III-V diluted magnetic semiconductor based heterostructure

Based on the mean field approximation, we investigated analytically the spin-transport of holes through heterostructure formed by magnetic layers Ga_(1−x)Mn_xAs separated by a non-magnetic spacer GaAs. Injected holes of up (down) spin have different transmission coefficient which oscillates for spin-down and increases fast for spin-up. The significant quantum size and (RKKY) interaction are considered simultaneously. The results indicate also that as the strength of the magnetic and non-magnetic layers increases, the spin-transmission changes. The results can be used to create efficient spin-filters.     

A transmission line model for arrays of rectangular microstrip antennas

A very efficient transmission line model for the analysis of arrays of rectangular microstrip antennas is presented. The structure of the model is discussed, and its validity is proved. This is done for the isolated microstrip antenna as well as for the coupling between antennas. Then follows a discussion of the numerical efficiency. And finally a numerical example shows the effect of mutual coupling on the impedance and radiation pattern of a 21 element Chebyshev array at different scanangles.     

Conductive adhesives for through holes and blind vias metallization

In the paper we propose the idea of “metallization” of the mechanically drilled through holes and the laser drilled blind holes by isotropic conductive adhesives in PCB manufacturing. Such processes can be used instead of electrochemical plating processes and are environmentally friendly. The investigations show that the filled through holes have the average resistance of about 100 mΩ while filled blind vias have average resistance of about 1 Ω in the case of PCBs with pure Cu pads. Better results were obtained if the Au pads metallization was applied onto the Cu layer. In that case the average fill resistance for through holes diameter 0.5 mm and 0.8 mm are about 50 mΩ and for vias 0.3 mm about 150 mΩ. The results are very promising for practical application.     

Image transmission with the subwavelength resolution in microwave,terahertz, and optical frequency bands

An image transmission principle related to the transformation of the spatial spectrum of a source into modes propagating in a metamaterial with a flat isofrequency contour is proposed. This principle makes it possible to obtain a resolution much smaller than the wavelength. The proposed principle is implemented in the microwave, terahertz, and optical frequency bands with the use of a medium consisting of parallel metal wires. It is shown that the subwavelength transmission of images can be achieved in the visible optical band via the use of a periodic structure consisting of successive metal and dielectric layers. The resolution, operation bandwidth, and sensitivity to losses in component materials are estimated for all the proposed systems. The applicability of such structures in medicine, in near-field microscopy, and as components of optical data storages with increased capacity is considered.     

Image transmission through ionospheric channel

An operational system for image transmission through the ionospheric channel is presented. For a range of 780 km, the 'high' data transfer rate attains 30 kbits/s in a 9 kHz bandwidth with the implementation of a blind spatio-temporal equalisation based on the constant modulus algorithm. This value significantly exceeds the current standard for HF modems (4.8 kbits/s). The quality of the transmitted images appears to be good compared with the original.     

基于线网拆分的数字水印增强技术

随着当今SoC(片上系统)设计理念的广泛深入,IP(知识产权芯核)复用在芯片制造行业的应用也日益成长,IP保护技术因防止IP非法盗用而变得至关重要.文中介绍一种基于版图设计的IP保护数字水印技术,通过对线网的拆分增加数字水印嵌入的概率,成功实施IP保护.在IBM-PLACE 2.0 Benchmark Suites上的试验结果表明,数字水印嵌入的成功率大大得到了改善.     

Enhanced transmission characteristics of on-chip interconnects withorthogonal gridded shield

On-chip interconnects over an orthogonal grid of grounded shielding lines on the silicon substrate are characterized by full-wave electromagnetic simulation. The analysis is based on a unit cell of the periodic shielded interconnect structure. It is demonstrated that the shielding structure may help to significantly enhance the transmission characteristics of on-chip interconnects particularly in analog and mixed-signal integrated circuits with bulk substrate resistivity on the order of 10 Ω-cm. Simulation results for the extracted R, L, G, C transmission line parameters show a significant decrease in the frequency-dependence of the distributed shunt capacitance as well as decrease in shunt conductance with the shielding structure present, while the series inductance and series resistance parameters are nearly unaffected. An extension of the equivalent circuit model for the shunt admittance of unshielded on-chip interconnects to include the effects of shielding is also presented     

多节点声呐阵列信号光传输系统设计与应用(本期优秀论文)

针对水下探测系统中多节点声呐阵列信号传输数据量大、传输距离远的要求,提出了一种基于低压差分信号(Low Voltage Differential Signaling,LVDS)传输结合光纤的远距离高速传输方式。鉴于声呐数据类型的多样性,在使用市面上通用光转换设备可能带来可靠性和资源浪费的情况下,结合声呐阵列自身的特点,设计了一套新的光传输系统,即用一根光纤就能实现所需的不同类型的声呐数据的双向传输。     

The picosecond pulse transmission on the conductor-backed coplanar waveguide with via holes

-The picosecond pulse propagation on the conductor-backed coplanar waveguide (CBCPW) with via holes is investigated. For this purpose, an empirical dispersion formula by fitting measurement data is proposed and Gaussian picosecond pulse transmissions on the CBCPW with via holes are simulated. By comparing the modeling data with the simulation result by the reported formula, we verify the usefulness and effectiveness of the proposed expression.     

S-parameters characterization of through, blind, and buried via holes

A method for de-embedding the scattering parameters matrix for single-end or differential through, buried, and blind via holes in multilayer printed circuit boards for high-speed digital applications is presented. The proposed technique starts from a measurement or simulation of the structure containing the discontinuity and, after the structure's partitioning, extracts the scattering parameters of the required discontinuity. The procedure is applied to different kinds of single-ended and differential via holes and is validated by measurements. The finite integration technique is used to perform the needed three-dimensional electromagnetic simulations. Due to its reduced CPU time, the proposed methodology is suitable for a parametric analysis on the electrical performance of the via hole discontinuities and it gives useful results for the extraction of accurate computer-aided design models.     

Enhanced differential chain coding for transmission of high qualityline graphics

An enhanced differential chain coding (EDCC) scheme is developed for transmission of high-quality line graphics. Experiments showed that, compared to DCC with a resolution of the enhanced graphics adapter (EGA: 640×350 pixels), EDCC with a resolution of 2100×1536 pixels gives a much higher quality with a modest extension in storage and transmission capacity