电磁干扰抑制技术及整改(五)

随着光电技术的迅速发展、传感器的不断更新,以及现代军事装备电子化程度的大幅度提高,电子设备之间的电磁干扰问题越来越突出。电磁兼容设计是一个不可或缺的环节,它能避免设备的误动作、图像噪声等,     

压缩冬季直埋光缆线路障碍抢修历时的措施

冬季直埋光缆线路障碍抢修,最困难的问题就是冻土挖掘。本文通过对破碎机、混凝土链锯工作性能的分析,得出了利用破碎机、混凝土链锯进行冻土挖掘可提高冻土挖掘速度,大幅度压缩冬季直埋光缆线路障碍抢修历时的结论。     

反辐射导弹破片毁伤地面目标仿真方法

针对地面复杂电子装备易遭受破片毁伤这一特点,且为有效解决复杂装备战场抢修研究战场损伤数据缺乏的问题,基于现有研究成果,完善了地面目标破片损伤概率模型,提出了地面复杂电子装备几何模型描述方法、战斗部起爆规律、战斗部破片仿真方法及目标损伤仿真方法,并开发了某型装备损伤仿真平台,验证了破片毁伤地面目标仿真方法有效性,研究成果将为破片毁伤研究及地面装备战损研究提供支撑。     

基于IMS的下一代网络

IMS(IP Multimedia Subsystem)是IP多媒体系统,是一种全新的多媒体业务形式,它能够满足现在的终端客户更新颖、更多样化多媒体业务的需求.目前,IMS被认为是下一代网络的核心技术,也是解决移动与固网融合,引入语音、数据、视频三重融合等差异化业务的重要方式.但是,目前全球IMS网络多数处于初级阶段,应用方式也处于业界探讨当中.     

High Temperature Superconducting Magnetic Energy Storage and Its Power Control Technology

High temperature superconducting （HTS） power inductor and its control technology have been studied and analyzed in the paper. Based on the results of simulations and practical experiments, a controlled release scheme has been proposed and verified for developing a practical HTS SMES prototype.     

你所应该了解的OFDM与MIMO

虽然无线通信技术一直都在不断发展,但当前却处于一个前所未有的变革期,新兴的4G空中接口如WiMAX、LTE、UMB、802．20、WiBRo以及下一代PHS等等都有一个共同的特点：即都是基于正交频分多址接入（OFDMA）、都采用MIMo（多入多出）技术、都具有“扁平化架构”且均基于IP（互联网协议）。     

Growth and dielectric properties of Ta_2O_5 single crystals grown by laser heated pedestal growth technique

Ta2O5 single crystals have been grown by the laser heated pedestal growth (LHPG) technique up to several centimeters length with diameter of 1.1 mm. The crystal, characterized by X-ray diffraction, dielectric measurement, and thermal expansion analysis, has Htri-Ta2O5 symmetry. Dielectric permittivity, loss tangent along [001] and [110] direction were investigated over the temperature range from -80 ℃ to 100 ℃. Large dielectric anisotropy in Ta2O5 single crystal was observed. At room temperature, the dielectric permittivities (1 MHz) along [001] and [110] are 33.2 and 231.9, respectively. The reason of dielectric enhancement in Ta2O5 crystal grown by LHPG was also discussed.     

Microwave Performance of Double δ-Doped High Electron Mobility Transistor With Various Lower/Upper Planar-Doped Ratio Designs

The microwave noise, power, and linearity characteristics of pseudomorphic high electron mobility transistors (pHEMTs) with various lower/upper planar delta-doped ratios were systematically evaluated and studied. By varying the lower/upper delta-doped ratio from 1:1 to 1:4, both Schottky gate turn-on voltage V_ON and breakdown voltage V_BR were reduced. In addition, higher upper delta-doped design is effective in improving the device current density, transconductance, output power, and power-added efficiency; however, this design also scarified the flatness of transconductance distribution and Schottky performance, resulting in a degradation of device linearity. As to the noise performance, after increasing the upper delta-doped concentration by more than 2 times 10¹² cm^-2, the minimum noise figure NF_min can be reduced to a stable range, and higher current density cannot efficiently improve the noise performance. Although the 1:4 design provided the largest power density of pHEMT, its high gate leakage current at high input power swing limited its linearity, and 1:3 design achieved the best linearity performance.     

Simulation Demonstration and Experimental Fabrication of a Multiple-Slot Waveguide

A multiple-slot waveguide is presented and demonstrated through theoretical simulation. Taking a double-slot waveguide as an example, the results show a nearly 30% enhancement of optical intensity compared with the traditional single-slot waveguide with the same slot gap width. Therefore, the E-field intensity of the slot can be increased by adding another smaller slot. A double-slot waveguide with oxide and air as low index slot materials is realized experimentally and the formation processes of the slots are analyzed.     

Leaky modes of optical waveguides with varied refractive index for microchip optical interconnect applications – Asymptotic solutions

In two-dimensional optical waveguides with the varied refractive index, approximate analytic solutions of the leaky modes are derived by using an asymptotic analysis for both transverse electric (TE) and transverse magnetic (TM) modes. Numerical simulations show that the asymptotic solutions of the leaky modes are quite close to the exact ones. The results are useful in the eigenmode method, where the leaky modes appear if a perfectly matched layer (PML) is used to terminate the transverse directions of optical waveguides.