Design and experimental investigation of a multibeam integrated reflector antenna of the millimeter wave band

A multibeam integrated reflector antenna operating in the millimeter wave band is considered. The antenna consists of a radiating array, a planar mirror, and a multichannel feed. The results of simulation of a radiating array of slots in a metal screen are presented. The array is manufactured on the basis of a medium with forced refraction, including a double-slot array, which can radiate along the normal to the array plane. Operation of the array in the multibeam mode is analyzed. It is shown that application of a medium with forced refraction increases the array aperture efficiency in this mode. The results of the design of a planar two-layer mirror are presented and the mirror’s quality indices are estimated. A multichannel radiator designed as an array of planar H-plane horns is studied. The results of simulation of such a radiator with the help of an approximate technique and numerical solution of an electromagnetic problem are considered. The design of the multibeam antenna and its experimental characteristics are presented.     

非球面齐明透镜的设计

鉴于过去文献只对非球面消球差透镜做了分析,根据初级像差理论给出了非球面齐明透镜(同时消球差和彗差)初始结构的求解方法,包括非球面齐明单透镜和非球面齐明双透镜的求解方法;并利用Zemax光学设计软件验证了这种求解方法的正确性.通过大量的计算给出了各种关系曲线,并分析了相对口径与透镜球差的变化关系,这些分析对光学系统的设计都是有益的.     

An experimental study of collinear and planar arrays

Measurements are described that serve to verify a recently reported new theory of arrays of arbitrarily located parallel elements especially including ones that are collinear and staggered. Since the theory takes full account of the effects of mutual coupling in determining the distributions of current in each element of an array, the experimental studies involved the determination of distributions of current and charge as well as admittances and field patterns. Since the theory should be a good approximation for dipole elements well over a wavelength long, complete measurements are reported for arrays of both half-wave and full-wave elements in collinear and planar arrangements. Experimental and theoretical results are in good agreement.     

An experimental study of planar impact of a robot manipulator

An experimental study of planar impact of a robot manipulator with a stationary rigid surface is presented. Using the data collected from a series of experiments, this paper investigates the post-impact behavior for different pre-impact conditions such as the configuration of the robot, the angle and the velocity of impact. A better understanding of the post-impact behavior for various pre-impact conditions can lead to improved control strategies during impacts in robotic manipulation. Potential applications of this study include robotic assembly and contact tasks. Further, this study could be seen as a preliminary experimental work on impact of general kinematic chains.     

Design of aplanatic waveguide Fresnel lenses and aberration-freeplanar optical systems

A modification of the waveguide Fresnel lens design that has phase-shifting zones placed on the curved contour is suggested. It is shown that the selection of a suitable shape for this contour allows coma aberration to be eliminated. Computer simulation results are presented to demonstrate the significant improvement of the optical characteristics for curved contour lenses. The aplanatic homogeneous refracting waveguide lenses are also considered. It is found that thick aplanatic refracting lenses and the proposed Fresnel lenses have field curvature aberration of opposite sign. This fact allows planar optical systems free from low-order aberration to be designed by combining refracting and Fresnel lenses. An algorithm for producing such a system is presented     

Analysis and experimental evaluation of a new planar piezoelectricaccelerometer

The behavior of a new planar piezoelectric accelerometer is investigated, both theoretically and experimentally. The proposed accelerometer is composed of a piezoceramic ring filled, in its inner space, with a seismic mass. The theoretical analysis has been carried out by using a matrix model of the radial symmetric modes of the thin piezoceramic ring, proposed by the authors (1996). The numerical results obtained for the empty ring show that, with the response being constant, the bandwidth increases when the annulus radius increases. On the contrary, by inserting a high-density and stiffness seismic mass, both the response and the bandwidth increase by increasing the percent quantity of the seismic mass. The measurements of admittance and sensitivity, carried out on a test specimen, validate the computed results and demonstrate that the accelerometer is planar. Finally, an accelerometer composed of two of such elements, stacked and connected in parallel, has been realized     

Design and experimental confirmation of a novel switched hyperchaotic system

To generate complex pseudo-noise (PN) sequences for chaos-based communications, this article presents a novel switched hyperchaotic model, which is constructed based on a modified Chen system by introducing a dynamical controller. The system consists of two different hyperchaotic subsystems and can change its behavior randomly via a switching function. Basic dynamical behaviors of the hyperchaotic system are further investigated. Furthermore, the switched system is confirmed by its positive Lyapunov exponents and laboratory measurements by an electronic circuit.     

平面螺旋天线的设计与实现

平面阿基米德螺旋天线具有极宽的工作频带，然而其匹配平衡电路的宽频带实现则较难，尤其是在加反射腔以使其单向辐射时。在4-6GHz范围内仿真并实际制作出了用于某S波段雷达系统单向辐射的平面螺旋天线，给出了设计参数值、仿真结果及实测结果。     

Design and performance of a planar star mixer

This paper describes the realization of a hybrid star mixer as a planar circuit. The mixer has a minimum conversion loss of 5 dB and, for a conversion loss of less than 9 dB, spans over 2.2 GHz in IF bandwidth and 8 GHz in RF/LO bandwidth. The mixer employs a novel, planar balun structure, similar to conductor-backed CPW, that is suitable for realization as a monolithic circuit     

An experimental study of a pulse compression scatterometer system

The ideal scatterometer, operating from either an aircraft or a satellite platform, should be capable of making rapid, accurate estimates of the sea backscatter cross sectionsigmaover as wide a range of grazing anglespsias possible. Efficient operation over a large range of grazing angles is desirable because 1)sigmabehavior for90deg geq psi geq 70degyields rms gravity wave slope information and is an indicator of sea state and 2)sigmabehavior for70deg geq psi geq 0degyields data on surface wind magnitude and direction as well as information about the power spectrum of the sea. A "hybrid" estimation procedure has been developed for pulse compression radars which uses both frequency and spatially decorrelated samples ofsigmato provide an unbiased estimate ofsigmahaving minimum variance over the entire range of grazing angles for which radar reception is not noise-limited.     

Design and quasi-static characteristics study on a planar piezoelectric nanopositioner with ultralow parasitic rotation

This paper presents a particular mechanism design which is inherently inclined to have no parasitic rotation. The flexure-based stage comprises symmetric flexure guiding mechanism and two piezoelectric stack actuators. The layout of the stage is evaluated by finite element analysis, and the results indicate that the proposed design exhibits ultralow parasitic rotation. A prototype of the stage is then fabricated, and its performance is tested. Experimental results show that the stage has a stroke of 500 μm × 500 μm and the crosstalk is less than 1%. The maximum parasitic rotation is ±1.2 arcsec at a stroke of 500 μm.     

一种小型平面超宽带天线的设计与研究

提出了一种新颖的小型平面超宽带(UWB)天线.该天线由微带槽天线的基本结构变形而来,为获得超宽带频率特性,设计时馈电微带线采用了渐变结构的叉形调谐支节,金属底板的开槽设计成对称多边形.首先通过数值计算来获得最佳的天线几何尺寸,并制作了实际的样品.对天线的反射特性、方向图以及增益都进行了测试,然后利用时域有限差分(FDTD)方法计算了天线收发脉冲信号的保真度.研究结果显示该天线具有良好的超宽带特性.     

Structure of a multibeam adaptive space-time processor

It is shown that an adaptive multi-input, multi-output space-time processor (beamformer and filter) consists of a multi-input, multi-output adaptive processor and a nonadaptive beamsteering operator. The adaptive processor is determined by the spatial and temporal properties of the noise field; whereas, the beamsteering operator is determined a priori by the desired beamsteering directions.     

场分布扫描套管腐蚀检测系统设计和实验研究

场分布扫描法是一种基于多频电流源激励下电流密度分布的套管在线腐蚀检测方法。设计场分布扫描套管腐蚀检测系统,为了初步验证场分布扫描法对腐蚀的可检测性,进行了穿孔实验。实验结果表明,场分布扫描法能够检测穿孔腐蚀,设计的电极系和检测系统对内直径为16.8 cm的金属套管上直径为6 mm的穿孔有较强的电敏感性。     

基于CPLD的接口实验系统的设计

本文以CPLD和单片机为控制核心构建一个可供进行单片机实验和EDA实验的系统.该系统由单片机,CPLD,温度传感器,步进电机及驱动,存储器,串口,AD,DA,语音输入输出,及人机交互部分组成,能够完成一系列从简单到复杂的实验,包括C51和Verilog HDL,在熟练掌握开发板基本实验的前提下,能够进行两个难度较大的实验,包括波形发生器和语音回放.     

Design of a high-frequency planar power transformer in multilayertechnology

A high-frequency power transformer using multilayer printed circuit board (ML-PCB) technology is presented for applications in switched-mode power supplies operating at frequencies up to several megahertz. The mechanical configuration of laboratory prototypes is discussed, as well as the electrical, parasitic, and thermal behavior. The focus is on the leakage inductance, since the analysis of other aspects is relatively simple. Test results show that the transformer has high efficiency, low leakage inductance, good thermal behavior, and good line insulation properties. The topology enables the designer to make a trade-off between leakage inductance and interwinding capacitance. Due to the well-defined geometry, parasitic interwinding capacitance and leakage inductance are reproducible and can be computed relatively easily     

平面超宽带天线的设计与研究

提出了两种新型的平面超宽带(UWB)天线,这两种天线的馈电单元和辐射单元都采用了矩形与圆形的组合结构,使得天线的工作带宽展宽.通过数值分析和实验结果表明,两种天线可获得较宽的工作带宽,能满足UWB天线3.1～10.6GHz的带宽要求.同时,具有良好、稳定的全向辐射特性和较高的增益,有较好的实用价值.     

On the radiation pattern of a multibeam antenna

The optimum radiation of a lens antenna with an array feed ofMelements is desired, which will exhibit maximum gain in a number (k) of specified directions and nulls in other (j) specified directions. This optimum is not derived; however, a condition for the optimum is shown to be some superposition of just (k + j) individual radiation patterns where each individual pattern is obtained by a separate excitation set of allMfeed elements such that the gain is maximized in each of the (k + j) directions. (The feed array excitation set for each of the (k + j) maximum gain individual patterns is derived.) Thus the number of unknown feed excitation coefficients is reduced fromMto (k + j).