Miniature multi-element antenna for wireless communications

We present a novel broad-band miniature antenna and employ it in a multi-element geometry with diversity capabilities for wireless communications. This antenna (diameter < 0.2 λ and thickness < 0.06 λ) consists of two stacked circular patches that create two cylindrical slots resonating at two slightly different frequencies, fed by a strategically positioned coaxial probe. An extensive parametric study and results for a prototype working at 5.2 GHz are presented. A multi-element geometry with two or four of such elements follows. Microelectromechanical system (MEMS)-based switches located within its geometry can not only change the working frequency of the design, but also activate a particular radiation beam depending on their specific location (resonant slot-aperture or feed line). Simulation results of a four-element antenna with dimensions 0.8 λ × 0.8 λ × 0.06 λ and a frequency band operation from 5 to 6 GHz are presented and compared to an experimental prototype. Circuit and radiation characteristics are discussed in terms of reconfigurability and diversity capabilities     

A reconfigurable slot aperture design over a broad-band substrate/feed structure

A novel dual-band reconfigurable aperture (RECAP) design is introduced for operation over a two-octave bandwidth. The proposed RECAP consists of interleaved crossed-slot elements for dual-polarized and broad-band array operation without grating lobes. The dimensions of the array elements can be reconfigured by using radio-frequency switches such as microelectromechanical systems or PIN diodes. The array elements along with the switches are integrated into the top layer of a multilayered composite structure consisting of passive, resistively loaded frequency selective surface (FSS) elements that form a broad-band ground plane system. Excitation is provided through a broad-band balanced/matched feed, and reconfiguration allows for broad-band operation using the same FSS substrate. Besides the FSS substrate, shorting pins can be employed within the cavity to enhance gain performance. Significant analysis and understanding of the FSS/slot array configuration is presented along with measurements that should serve as a reference in future developments of these layered arrays.     

基于微波整流的半导体开关无线控制

针对有源电子标签及传感器节点低功耗唤醒模块的需求,设计了一种基于微波整流的半导体开关无线控制方法。通过微波整流之后的直流输出电压来控制半导体开关的状态,进而控制唤醒电路的直流电源通断,利用半导体开关关断状态下漏电流极低的特点,确保设备在休眠期达到极低功耗,从而延长标签及节点电源的工作时间。文中的微波整流设计主要以实现最大化直流输出电压为目标,整流天线部分采用双单元的整流阵列设计。仿真与测试结果表明,每一路天线接收到-18 dBm的射频功率时,直流输出电压可达到典型的CMOS开关控制所需的最低电平(1 V)。     

Pattern Reconfigurable Cubic Antenna

A new single-feed reconfigurable antenna for pattern diversity is presented in this paper. The proposed structure is based on a metallic cubic cavity which radiates through rectangular slots. The pattern reconfiguration is achieved with PIN diode switches by short-circuiting slots in their center. The designed antenna can switch between three different radiation patterns which radiate in a $4pi$ steradian range and can receive any incident field polarizations. A prototype of the antenna, including PIN diodes and operating in the 5 GHz band, has been built to demonstrate the feasibility of the concept. Measurements have been conducted and three-dimensional radiation patterns are provided. Diversity performances are evaluated by calculating the envelope correlation coefficient.      

A thermally-actuated latching MEMS switch matrix and driver chip for an automated distribution frame

This paper presents a thermally-actuated latching MEMS switch matrix together with an integrated driver chip for controlling these switches. The novel thermal actuators are heated by making use of a polysilicon heater underneath the structure, which results in a more stable actuation and a facilitated driving. The designed driver can generate adjustable latching waveforms which are needed to latch the switch into a closed or open state. As the thermal actuators in the MEMS switch require voltages up to 24 V, the high-voltage 0.35 µm  I3T50 technology of ON Semiconductor was used to fabricate the device. The driver, measuring 2 × 2 mm², contains 32 output drivers and can control a 4 × 4 latching switch matrix. This driver chip together with the latching MEMS switches were combined to create a prototype 2 × 2 double-pole single-throw latching MEMS switch matrix. The proposed MEMS switch matrix could be used in the fixed-access telecommunication network in which it can implement a compact automated distribution frame for connecting twisted pairs.     

On the limits of electronic ATM switching

This article discusses the principal advantages and limitations of electronic switching in asynchronous transfer mode (ATM) networks. Key design parameters of ATM switch implementations are defined, and their relationships with respect to performance, complexity, and cost are modeled and discussed. Design and implementation experience is reported on a very high-performance four-input, four-output ATM switch that has been designed as part of the DARPA-sponsored “Thunder and Lightning” project at the University of California, Santa Barbara. This research project is focused on the design and prototype demonstration of ATM links and electronic switches operating at 40 Gb/s per link (TDM), with potential scalability to 100 Gb/s. Such aggressive link rates are near the implementation limits for electronic ATM switches; they place severe requirements on switch architecture, particularly the buffering scheme     

Scalable optoelectronic ATM networks: the iPOINT fully functionaltestbed

Our prototype of a fully-functional asynchronous transfer mode (ATM) switch validates the design of a 128 Gb/s optoelectronic ATM switch. Optoelectronics, rather than all optical components, are used to simultaneously address all of the specific requirements mandated by the ATM protocol. In this paper, we present the Illinois pulsar-based optical interconnect (iPOINT) testbed, and present our results obtained for the prototype switch in a working environment consisting of an optical network of Sun SPARC Stations and other local and wide-area ATM switches     

Design of wavelength converting switches for optical burst switching

Optical burst switching (OBS) is an experimental network technology that enables the construction of very high-capacity routers, using optical data paths and electronic control. In this paper, we study wavelength converting switches using tunable lasers and wavelength grating routers, that are suitable for use in OBS systems and evaluate their performance. We show how the routing problem for these switches can be formulated as a combinatorial puzzle or game, in which the design of the game board corresponds to the pattern of permutation used at the input sections of the switch. We use this to show how the permutation pattern affects the performance of the switch, and to facilitate the design of permutation patterns that yield the best performance. We give upper bounds on the number of different wavelength channels that can be routed through such switches (regardless of the permutation pattern), and show that for 2/spl times/2 switches, there is a simple permutation pattern that achieves these bounds. For larger switches, randomized permutation patterns produce the best results. We study the performance of optical burst switches using wavelength converting switches based on several different permutation patterns. We also present a novel routing algorithm called the most available wavelength assignment and evaluate its benefits in improving the switch throughput. Our results show that for a typical configuration, the switch with the best permutation pattern has more than 87% of the throughput of a fully nonblocking switch.     

大规模可重构天线的开关数目缩减算法研究

提出了一种缩减大规模可重构天线开关数目以降低复杂度的方法,同时并不明显降低天线的可重构 能力。该方法通过剔除对天线可重构能力贡献较小的开关来实现,最终只保留在天线重构过程中起到重要作用的 开关。开关的重要性采用反射系数包络线相关函数来表征。为了验证该方法,仿真了一款具有40 个开关的可重构 微带天线。用该方法将开关的数目缩减到8 个之后,天线仍然能够完全覆盖所研究的频段范围,同时保持重构的反 射系数优于-20dB。     

Criteria for wide-band radial switch design

This paper presents criteria for the design of radial switches, such as can be used in electronically steered circular array antennas for satellite communications mobile terminals. The choice of the switching circuit and diode used in each channel is discussed and the required inductance for the diode shunt capacitance compensation for lower insertion loss is given. Analytical formulas are derived for the general case of an ideal transmission-line switch to show the dependence of the return-loss bandwidth on the choices of the line impedance. Important optimization criteria for lower insertion loss and increased bandwidth are drawn. The criteria have been used to guide the design of economical L-band microstrip switches for use in INMARSAT/MSAT antenna arrays, using low-cost printed-circuits and surface-mount plastic-encapsulated p-i-n diodes. Implementation results for insertion loss, reflection coefficient, and isolation between channels are reported     

低剖面极化可重构超表面天线

提出了一种低剖面极化可重构超表面天线. 天线由三部分组成:3×4金属矩形贴片阵列组成的超表面覆层、缝隙耦合天线和直流偏置控制电路. 电路包括8个PIN二极管开关组成的四对开关（PIN1,PIN2,PIN3和PIN4）和直流偏置线,通过控制上述四对PIN开关的工作状态,天线可以在线极化、左旋圆极化和右旋圆极化三种极化状态之间转换. 对天线样机进行了加工并给出了实测反射系数、实际增益、轴比和归一化辐射方向图,结果表明:天线在不同工作状态下的共享工作频带为4～5.4 GHz,?10 dB阻抗带宽为29.8%;3 dB轴比带宽为8.3%,从4.6～5 GHz;各状态下的实测增益相差不大,其平均增益都大于5 dBi. 仿真结果与实测结果吻合良好.     

A theoretical and experimental study of mutual coupling inmicrostrip antenna arrays

Each microstrip antenna element in the array is replaced by an equivalent magnetic current source distribution over a grounded dielectric slab derived from the electric field on the walls of the element as given by the cavity model. A dyadic Green's function is developed for a grounded dielectric slab, using the rectangular vector wave functions. The function is used to calculate the magnetic field due to the magnetic current distributions. The formula for mutual impedance based on the reaction concept is used to calculate the mutual coupling in arrays of antenna elements. Some measurements have been conducted for mutual coupling between two rectangular patches in the C-band. Calculated results are in excellent agreement with measurements, including those of other authors     

电子复合开关在电力高压配电网中的应用

针对机械开关和电力电子开关在10kV配电网应用中存在的问题,文章介绍了一种应用在10kV高压配电网中的复合开关。与机械开关和电力电子开关相比,该种复合开关的主要优点在于它具备了电力电子开关能够过零投切的优点,同时又具有机械开关工作稳定、无损耗等优点,从而使得开关及用电设备的寿命延长,具有很高的实用价值。     

A Ferroelectric Microwave Switch

The rapid variation of an admittance shunting a transmission line is a well-known technique for switching microwave power. The application of a switching voltage to a ferroelectric material provides a convenient means for rapidly varying an admittance between significantly different states. A multistub transmission-reflection-type switch actuated by a switching voltage of 1000 volts has been studied. The operation of the switch depends upon the ability of a ferroelectric variable capacitor to change its capacitance upon application of a switching voltage. A change in capacitance represented by a ratio of two to one results in substantial change in the input admittance of the prototype network shunting the transmission line. The prototype network is a shunt stub and is spaced nominally at /spl lambda/ /4 intervals along the transmission line to form a multistub switch. Each shunt stub includes a ferroelectric variable capacitance which employs lead strontium titanate (Pb/sub 0.315/Sr/sub 0.685/TiO/sub 3/) as the ferroelectric material. Both theoretical and experimental curves of isolation and insertion loss vs. frequency are given for two- and three-stub versions of the switch. For switching voltages of the order of 1000 volts, ferroelectric switches with an isolation of 40 dB, an insertion loss less than 1.0 dB, and a bandwidth of 10 percent are feasible.     

RF-MEMS switch design optimization for long-term reliability

This contribution presents an optimization strategy for the mechanical and geometrical characteristics of clamped–clamped dielectric-less RF-MEMS switches in order to enhance their reliability performances both in terms of switch properties control and long-term actuation behavior. The modifications mainly affect the switch membrane, which is made more robust, and the stopping pillar dimensions, while the switch dimensions are practically unaffected. In the case of the proposed ohmic switch, also the mobile contact region was redesigned in order to increase the contact force. Experimental measurements have demonstrated that the optimized version of the capacitive switch investigated shows an improved resistance to high bias voltages (up to 90 V), while the optimized ohmic switch shows a lower, more stable and more reproducible contact resistance. Long-term actuation measurements are analyzed in detail, proposing a model to evaluate the switch lifetime, which was found of the order of few years in the more conservative estimate in the case of capacitive switches. The lifetime estimates are less precise in the case of ohmic switches, mainly because the contact instability sums up with the charging contribution. In spite of the improved switch general properties, lifetime is however not increased with optimization. The most likely explanation is that the optimization strategy was aimed at reducing charge injection and charge non-uniformity, but other effects can be important in lifetime determination.     

An electronically switchable leaky wave antenna

We report an electronically switchable dielectric leaky wave antenna. The main beam angle can be electronically steered using p-i-n diodes. The diodes are used as switches to control the radiation from two sets of gratings with different periods, thereby switching the main beam angle. Beam steering is achieved at a single fixed frequency; no frequency sweeping is necessary. A microwave prototype demonstrates a 35° change in beam direction at 3.5 GHz. Measured antenna patterns agree with theoretical predictions. This approach should be scalable to millimeter-wave frequencies using diodes monolithically integrated on a semiconductor waveguide     

基于数字加速度计的智能倒置开关

倒置开关是实现放入式电子测压器电源控制和低功耗的关键部件,已研制的几种倒置开关在靶场试验中多次出现上电不可靠的问题。为了提高膛压测试的可靠性,运用微机械数字加速度计设计了一种智能倒置开关,该开关采取双重判断机制对上电条件进行判断,可靠性高。利用马歇特锤试验机进行了抗冲击性能检测,结果表明,该开关最大能承受45000g。设计的可靠性检测系统,能模拟实际工作环境,对倒置开关进行筛选,提高了工作可靠性。该开关可推广应用于其它存储测试系统。     

一种双频左/右旋圆极化可重构环形缝隙微带天线

设计了一种频率比为1.9的双频左/右旋圆极化可重构环形缝隙微带天线,其在高频段和低频段分别工作于线极化和圆极化状态。在该天线中,环形缝隙和相互正交的四个缝隙臂将接地面分为五部分,缝隙臂上跨接两对PIN二极管开关和隔直电容。通过二极管开关的控制,天线在低频频率上可实现左/右旋圆极化的切换,在高频频率上则可保持其线极化性能不变。实验结果表明,天线在1.6 GHz的低频段上具有12.5%的3 dB轴比带宽,在3.06 GHz的高频段上其–10 dB阻抗绝对带宽为100 MHz,成线极化状态,辐射方向图近似不变。     

Diversity gain from a single-port adaptive antenna using switchedparasitic elements illustrated with a wire and monopole prototype

A new concept in single-port adaptive antennas using parasitic elements with switched terminating impedances is presented including results from a concept prototype. Each parasitic element can be effectively terminated in three impedance values. The antenna concept provides multiple radiation patterns with a single RF signal port without the need for RF switches or phase shifters in the direct RF signal path. Impedance variations in the active antenna element are minimized by use of only rotationally symmetric configurations. Measured patterns are used to demonstrate the performance improvement expected using switched diversity combining in a simulated uniform scattering scenario. The concept prototype having one active element and four parasitic elements, is shown to have equivalent diversity performance to between three and four uncorrelated branches     

Dilated Networks for Photonic Switching

We present some novel architectures for rearrangeably nonblocking multistage photonic space switches implemented using arrays ofTi:LiNbO_{3}directional couplers. Multistage networks, studied mostly in the electronic domain, are obtained by minimizing the number of 2 × 2 elements needed to implement a switch. Unfortunately, straightforward extensions of these networks to the photonic domain show that the switch size has to be severely limited by the crosstalk in each of theTi:LiNbO_{3} 2 times 2switching elements. Our networks, on the other hand, have a controllable (including almost zero) amount of crosstalk, low optical path loss, and an asymptotically optimal number of directional coupler switches for a given switch size. In addition, the switch has a simple control algorithm and its performance for light loading appears very promising. The switch is easily decomposable into smaller arrays of no more than two types, making it easy to partition the switch into chips. At the cost of a slight increase in crosstalk, the switch can be made single fault tolerant in terms of its ability to connect any input to any output.