Dual-band monopole antenna with shorted parasitic element

A printed dual-band C-shaped monopole antenna with a shorted parasitic element is proposed. The proposed antenna can provide two separate impedance bandwidths of 156 MHz (about 6.4% centred at 2.45 GHz) and 2048 MHz (about 37% centred at 5.5 GHz), making it easily cover the required bandwidths for wireless local area network (WLAN) operation in the 2.4 GHz band (about 3.4% bandwidth required) and 5.2/5.8 GHz bands (about 13% bandwidth required). Furthermore, the proposed antenna shows a low-profile of 635 mm above the ground plane. Details of the proposed antenna design and experimental results are presented and discussed.     

Shorted matrices in star and related orderings

A new class of shorted operators is considered. The shorted operator has an intimate relationship with electrical networks and has been extensively studied. In this work we consider the class of matrices with row and column spans in specified linear subspaces and dominated in a given partial order by a matrixA. If this class of matrices has an unique maximal element under the partial order, then this maximal element is called the shorted matrix ofA relative to the given linear subspaces and the relevant partial order. We study the shorted matrix under the star order of Drazin, the minus order, and also under partial orders induced by the minimum norm and least squares g-inverses. The parallel sum of matrices is intimately related to the shorted matrix and results are given for parallel addition.     

Small square dual spiral printed antennas

A novel shorted dual spiral printed antenna is presented. The antenna consists of two interleaved shorted spiral radiators and a feed network etched on a high dielectric material below the ground plane. A 10 dB return loss bandwidth of 9.2% has been achieved with an omni-directional radiation pattern. The proposed antenna is 28% smaller than a conventional shorted patch antenna, making it very desirable for mobile communication handset terminals     

A Decomposition Method for Computing System Reliability by a Matrix Expression

A decomposition method using a matrix representation for computing the reliability of a redundant system is proposed. The system is decomposed into two subsystems according to up- and down- states of a keystone element. This is repeated recursively until all subsystems have known reliability. The criterion for choosing the keystone element and an algorithm for decomposing a system are described.     

Finite Element Analysis of Planar Microwave Networks

The port admittance matrix of a planar network is formulated in terms of certain harmonic functions related to the port voltages and the network geometry, together with the natural modes of the network with all ports shorted. The necessary harmonic functions and eigenfunctions are found using a finite element technique, for which general-purpose computer programs already exist. An advantage of the method is that the admittance matrix appears in partial-fraction form with geometric data separated from frequency, leading to inexpensive computations where recalculation at various frequencies is required.     

A Novel Depletion-Mode MOS Gated Emitter Shorted Thyristor

A Novel MOS-gated thyristor, depletion-mode MOS gated emitter shorted thyristor (DMST),and its two structures are proposed. In DMST,the channel of depletion-mode MOS makes the thyristor emitter-based junction inherently short. The operation of the device is controlled by the interruption and recovery of the depletion-mode MOS P channel. The perfect properties have been demonstrated by 2-D numerical simulations and the tests on the fabricated chips.     

Ladder-shaped network for ESD protection of millimetre-wave CMOS ICs

A compact ladder-shaped electrostatic discharge (ESD) protection circuit is presented for millimetre-wave integrated circuits (ICs) in CMOS technology. Multiple shorted shunt stubs form a ladder network together with series stubs as ESD protection that discharges current/voltage pulses caused by an ESD event, while at the same time the network is embedded as part of the matching circuit for a normal operation. A 60 GHz low-noise amplifier using a 90 nm CMOS process is demonstrated with the proposed ESD protection methodology that introduces less than 1 dB insertion loss. Owing to the ESD current distribution through multiple shorted stubs, the proposed methodology is useful to millimetre-wave ICs with advanced CMOS technology that suffers from higher sheet resistance of the metal layers.     

A Novel Depletion-Mode MOS Gated Emitter Shorted Thyristor

More attention has been given to the MOS-gated thyristor and several device struc-tures of MOS-gated thyristor have been reported,such as MOS-controlled thyristor(MCT) [1 ] ,depletion-mode thyristor (DMT) [2 ] ,field assisted turn-off...     

A shorted waveguide-stub coupling mechanism for narrow-band multimode coupled resonator filters

A shorted waveguide-stub coupling mechanism is presented for implementing narrow-band multimode coupled cavity filters without coupling screws. The coupling element is a shorted rectangular waveguide stub placed in the end walls of cylindrical filter cavities, using perturbation of the magnetic fields to obtain coupling between degenerate modes. This structure is well suited to analysis and design with the efficient and accurate mode-matching method. Coupling coefficients and resonator frequencies can be controlled by varying cavity dimensions and the length, width, and depth of the rectangular coupling element. The accuracy with which the coupling can be realized and the elimination of coupling screws reduce the amount of tuning substantially. A third-order Chebyshev filter, realized in a triple-mode cavity with no coupling screws and only two tuning screws, is presented to verify the use of the coupling structure.     

Small dual L-shaped printed antenna

A novel shorted dual L-shaped printed antenna is presented. The antenna consists of two L-shaped shorted patches and a feed network with a 180/spl deg/ phase difference applied to each antenna probe, etched on a high dielectric substrate located beneath the ground plane. A 10 dB return loss bandwidth of 16.6% has been achieved. The measured cross-polarised fields are 15 dB below the co-polarised levels     

无线局域网应用的接地平面单极天线的设计

提出了一种应用于无线局域网(WLAN)的新型低成本多频段天线,采用斜切角接地的平面单极结构,天线顶部折返成水平面内的两个对称矩形单元来降低高度。同时,通过在垂直辐射单元表面开L形槽的方法,实现了无线局域网高低两个工作频段覆盖的需求。天线在各工作频段内具有良好的全向辐射特性。实测和仿真结果基本吻合,从而验证了这种设计方法的有效性。     

Multiband Meandered Monopole Antenna for Mobile Applications

A multiband meandered monopole antenna is proposed for digital video broadcasting handheld (DVB‐H), global positioning system, personal communications service, wireless broadband (Wibro), and wireless local area network (WLAN) applications. The proposed antenna consists of a meandered line, a shorted length strip line, and a conductor strip between a meandered line and a microstrip feed line. By tuning a short strip and a conductor, a multiband impedance matching is achieved. The proposed antenna has an omnidirectional radiation and yields an antenna gain of greater than ?3 dBi in the DVB‐H band and 4.5 dBi in the Wibro and WLAN bands. Details of the proposed antenna design and experimental results are presented.     

Shorted fractal Sierpinski monopole antenna

A novel configuration of a shorted fractal Sierpinski gasket antenna is proposed. Using only half the structure of a conventional Sierpinski gasket, the antenna is folded over to be parallel to the ground plane, to form an element that is, in some ways, similar to the inverted L antenna. A shorting pin is then placed at the far end of the antenna. A quasi log periodic resonance behaviour is observed     

有线电视双向HFC综合信息网前景展望

通过对双向HFC网络的技术优势、结构特征、功能特点等方面的分析 ,并结合国内外有线电视双向建设和业务开展经验及黔东南州电视台多年来对有线电视网络建设及业务运营的不断探索 ,依据广电总局印发的“有线广播电视网改造指导意见” ,提出有线电视双向HFC网络改造建设的重点、步骤及误区 ,重点阐述了当前网络建设与数字电视发展的关系 ,并展现了有线电视双向HFC综合信息网的广阔前景     

A 40 ns 64 kbit junction-shorting PROM

The memory is organized as 8192 words/spl times/8 bits. A memory cell consists of a programmable element composed of a p-n junction diode and a vertically connected p-n-p transistor. During programming, the programmable element is changed from the current-blocking state of a reverse diode to the current-conducting state of a shorted junction diode by using the diffused eutectic aluminum process (DEAP). With a selective power switching dual-stage decoder, the power dissipation in the decoder circuit was reduced to 40% of a conventional decoder without power switching. The power saved was used to speed up the multiplexers and the output buffers.     

Stacked shorted patch antenna

A novel stacked shorted patch antenna is proposed and investigated both theoretically and experimentally. The new antenna has significantly greater bandwidth than a conventional shorted patch and its behaviour is less susceptible to manufacturing errors. The stacked shorted patch is small in size and, thus, is suitable for mobile communication applications     

网络安全态势要素指标体系研究

针对网络安全态势评估指标体系的不完善和难以选取及构建等问题,以相关标准和规范为基础,从系统安全机制出发,按照既定原则,提出一种网络安全态势要素指标体系构建方法,并给出了网络可用性态势要素数据获取和指标值的计算方法。实验表明,网络安全态势要素指标体系的构建具有一定的科学性,为网络安全态势评估提供了一种新的数据解决途径。     

A numerical approach based on transient thermal analysis toestimate the safe operating frequencies of thyristors

The spatio-temporal distribution of temperatures in high-power SCRs used for switching high di/dt current pulses were simulated using the finite element method (FEM). Two types of SCRs, with amplifying gate (unshorted device), and without amplifying gate (shorted device) structures, were analyzed. The details of the numerical simulation, such as the meshing strategy, the heat source model and the boundary conditions are discussed. Based on the analysis, the failure temperature of the unshorted device was computed to be 1100°C. The peak temperature in the shorted device was, however, found to be 335°C. The instantaneous cooling cycles of the devices and their cooling time constants, as obtained from the simulations, are presented. Based on these parameters, the safe operating frequencies of these devices were estimated     

Performance evaluation of multi-hop csma/ca networks in fading environments

The performance of multi-hop CSMA/CA networks has in most cases been evaluated via simulations, or analytically using a perfect collision channel model. Using such methods, one can neither have access to the capture nature of the terminals nor evaluate the performance of the network in a fading environment. In this paper a new analytical framework that takes into account these capture and fading effects is presented. The network investigated in this paper has an infinite number of nodes which is assumed to be spatially Poisson distributed. The approach is to develop analytical expressions for the transition probabilities between states of nodes in the network by approximating these states as a Markov chain. A fast algorithm to solve these equations is also given. Numerical results show that the model agrees with simulation results for both omni-directional networks and networks employing beamforming.     

Susceptibility analysis of arbitrarily shaped 2-D slotted screensusing a hybrid generalized scattering matrix finite-element technique

The electromagnetic susceptibility (EMS) inside slotted screens has been studied using a hybrid technique. The screen is characterized by a generalized admittance or impedance matrix, computed using the finite element method (FEM), which is then combined with a modal solution in free-space. The scattering matrix for the screen can then be easily computed. As a practical application, the electrical performance of a slotted square envelope has been studied. In general, it is shown that coupling to the interior of slotted screens is maximized at frequencies corresponding to resonances of the shorted screen, provided that the fields do not vanish near the aperture