一种新型超宽带喇叭天线的研究

提出一种基于H波导的新型超宽带喇叭天线以减小一般的超宽带天线如TEM喇叭天线侧向泄漏较大的问题.先在理论上研究了H波导用作超宽带天线的可行性以及参数选择的依据,然后利用FDTD方法研究了同轴探针激励的H波导的时域传输特性和截断的H波导及喇叭的辐射特性,得出该天线可用于超宽带天线,尤其是该天线具有较小的侧向泄漏,使其可以用作天线阵的单元的结论.     

Theoretical and Experimental Study of a Novel H-Guide Transverse Slot Antenna (Short Papers)

Transverse slots in the "upper" plate of a dielectric-loaded parallel plane waveguide (H-guide) operating in the dominant mode (zero cutoff frequency) are proposed as slot antennas. A new theoretical approach to the analysis of a single-slot antenna is presented, leading to explicit expressions for the antenna input impedance and radiation efficiency. The computed values of the VSWR and radiation efficiency are in good agreement with laboratory measurements. The radiation efficiency of a single slot exceeds 10 percent in the 8-11-GHz frequency band, reaching a 50-percent theoretically predicted maximum at the slot resonance frequency, when the guide is terminated by a matched load. Experimental checks prove that the leakage, or parasitic, radiation power level is less than -40 dB relative to the measured radiated power.     

Groove guide and H-guide: Supplementary information

Interest in groove guide and H-guide for application at millimeter waves is considerable at present. Hitherto unpublished material dealing with these waveguides is presented. The early history, patent applications, drawings and prototypes are described.     

Magnetopasma surface wave analysis for an H-guide structure containing semiconductor

The propagation characteristics of higher order magnetoplasmon surface waves have been studied for an H-guide structure. Hybrid TE-TM modes are found at frequencies above the cutoff value. We explore their non-reciprocal propagation characteristics as a basis for the design of non-reciprocal devices.     

Oversized waveguides and resonators for millimeter waves

If real monolithic systems^* turn out to be impractical at millimeter-wave frequencies, oversized waveguides and resonators are useful alternatives in component and system design. Low losses, high Q factors, and inexpensive manufacturing are their advantages. Starting with an explanation of the term “oversized”, the loss reductions, Q factors, inherently oversized guides, such as the H-guide and its modifications, excitation of higher-order modes, laterally oversized H-guides, and the effects of coupling are described. A brief consideration of applications concludes the presentation.     

Guided-Wave Experiments with Dielectric Waveguides Having Finite Periodic Corrugation

A planar dielectric waveguide having finite periodic rectangular corrugation is investigated analytically and experimentally, in case of surface waves propagating at an angle to the corrugation. In analytical considerations, a finitely corrugated guide is regarded as consisting of many step discontinuities connected by a length of uniform slab waveguide, and its propagation characteristics in the Bragg interaction region are derived from a cascaded connection of the transmission matrix expressing a step discontinuity. Although the present method takes only surface wave modes into account and neglects the wave with continuous spectrum, the calculated results show an excellent agreement with experimental ones which are performed for art H-guide in the microwave region.     

Nonradiative Dielectric Waveguide for Millimeter-Wave Integrated Circuits

A nonradiative dielectric waveguide is proposed in which dielectic strips are sandwiched between two parallel metal plates separated by a distance smaller than half a wavelength. Though the structure is substantially the same as that of the H-guide, it is based on a quite different principle of operation. This dielectric guide is particularly applicable in millimeter-wave integrated circuits, since it is not only small in size, but also allows bends and junctions to be incorporated into the circuits with very little radiation and interference. A design diagram is given. Losses and coupling coefficients of the strips are calculated, as well. Some basic circuit components, such as 90° and 180° bends and T-junctions, made of polystyrene strips, are measured to confirm their usefulness in millimeter-wave integrated circuits.     

Attenuation of the HE/sub 11/ Mode in the H-Guide (Correspondence and Author's Reply)

The properties of the lowest order hybrid mode of the H-guide line have been analyzed by Tischer in a number of papers. This type of transmission line has also been under investigation at this laboratory for some time and a number of discrepancies exist between our analysis and those of Tischer.     

Spectral-domain Green's function of magnetic type for NRD guidesand H-guides

Nonradiative dielectric guides and H-guides are widely used in millimeter-wave integrated circuits and antennas. To analyze the behavior of discontinuities, obstacles, and slots in such structures, an increasingly used mathematical formulation is the integral-equation approach, for which Green's function is required. Here, an efficient programmable full-wave Green's function, due to a magnetic-current element placed inside the dielectric layer, is derived in the spectral domain. In the derivation procedure, the field is divided into two parts: the incident and scattering fields. The contribution of the surface wave is included in the scattering part, while the singularity, when the field and source points are the same, is presented in the incident field part. By doing so, one can deal with the singularity caused by the source and surface-wave poles encountered in the integration separately and freely. The Green's function is then used to analyze the radiation characteristics of a single transverse slot in upper plate of the H-guide. The results obtained are in good agreement with experimental data available in literature     

Dielectric waveguide modulators at 95 GHz using LiNbO3

We describe electro-optic modulators at 95 GHz using LiNbO₃ in an H-guide configuration. We have observed 70% amplitude modulation at l KHz in a bridge configuration, corresponding to an induced phase shift of ±29°. The prospects for improved device performance will be discussed.     

Excess Surface Resistance Due to Surface Roughness at 35 GHz

The increase of the surface resistance of plane copper surfaces caused by mechanically generated surface roughness has been determined at 35 GHz by measuring and evaluating the Q values of an H-guide cavity with removable sidewalls. The sidewalls were ground one-directionally by using abrasive papers of various grades to produce various degrees of roughness. The rms values of roughess were measured mechanically and optically after calibration by microphotography.     

Bragg Reflection Characteristics of Millimeter Waves in a Corrugated H-Guide

The Bragg reflection characteristics of millimeter waves in a H-guide having a corrugated dielectric slab are investigated by the perturbation method of multiple scales. Brillouin diagrams in the vicinity of the Bragg frequency of the TM-TM-, TE-TE-, and TM-TE-mode couplings are shown. Validity of the theoretical predictions are confirmed by experiments carried out in the 40-50-GHz region. Typical frequency response at the stopband resulting from TM-TM-mode coupling is stop bandwidth about 380 MHz, with return loss about 2.1 dB at the Bragg frequency 47.3 GHz.     

基于MSP430单片机的多路数据采集系统的设计

介绍一种以MSP430单片机为核心的多路数据采集系统。系统由集成函数发生器ICL8038现场模拟产生一正弦波信号并通过LM331实现频率到电压的变换,从而供给单片机进行数据采集。系统采用单片机与上位机进行通讯,单片机负责对7路数据的采集、处理和控制显示,同时应答上位机命令。上位机面向用户,可以对系统进行控制,选择数据采集的方式。设计并实现了一种具有现场采集和显示并且采集方式可控制的多路数据采集器,该数据采集器具有硬件电路简单,采集精度较高,低功耗等特点,具有推广应用价值。     

单个非球面扩束透镜的设计

为设计单个非球面扩束(缩束)透镜,由光线折射定律矢量形式和对非球面折射特性的理论分析,提出了一种设计单个非球面扩束(缩束)透镜的新方法全面学习策略的粒子群算法,并用此方法设计出了线度小于170 mm缩束14.16倍的单个非球面缩束透镜,用光线追迹方法模拟了缩束或扩束过程。模拟结果表明,单个非球面透镜可以起到缩束或者扩束作用,全面学习策略的粒子群算法可用于非球面缩束透镜的设计。单个非球面透镜作为扩束镜使扩束系统结构大大简化,大大提高了出射光斑的均匀性。     

High bandwidth single polarization fiber with elliptical central air hole

A novel design of single polarization fiber is presented. The structure of the fiber comprises an elliptical central air hole with depressed cladding surrounding the core. Parameters that affect the performance of the single polarization fiber in terms of the location of the single polarization operating window and single polarization bandwidth are analyzed. The analysis results in the identification of a fiber design that can yield a single polarization bandwidth as high as 240 nm around 1550 nm.     

基于LM35的温度测量系统

在现代化的工业生产中，温度是常用的测量及被控参数。采用51单片机来对温度进行测量，不仅控制方便、组态简单灵活，还能够大大降低成本。据此介绍了一种温度传感器选用LM35、单片机选用AT89C52的温度测量系统，并详细介绍了该系统的硬件电路及软件设计。该系统的温度测量范围为O～99℃，可以精确到一位小数，体积小、成本低、工作可靠，可适用于工业场合及日常生活中。     

Cellular packet communications

The future of third-generation wireless networking is discussed. The vision of the third generation is a single set of standards that can meet a wide range of wireless access applications. Third-generation systems, in harmony with broadband integrated services digital networks, will use shared resources to convey many information types. A single network architecture will serve its users efficiently in many environments, including moving vehicles, indoor and outdoor public areas, residences, offices, and factories. A study of a switching architecture, referred to as a cellular packet switch, and a packet transmission technique, referred to as a packet reservation multiple access is discussed. By means of a design example, it is shown how these techniques can work together to meet some of the demands of third-generation systems     

激光光镊术简介

人们借助单一激光微光微光束与显微照相技术的共同配合，利用微激光束在透明微粒附近产生的梯度力，实现了对微小粒子的捕获及操纵。随着物理理论与技术的发展，所能操纵的粒子越来越小，对活性微体的损伤也在减小。目前这一技术不仅用来操纵原子、细菌、单细胞等，还在分子生物学、医学等领域中发挥着作用。同时非共轴多光束技术的引入，提高了这一技术操作的稳定性与方便性，为以后更广泛的应用提供了条件。