Utility of RF MEMS miniature switched capacitors in phase shifting applications

This paper demonstrates research carried out towards the development of switched capacitors having miniature dimensions. Such devices are based on the Radio Frequency Micro Electro Mechanical Systems (RF MEMS) technique which has gained prominence in implementing a wide variety of microwave and millimetre devices till date. Switched capacitors having standard or conventional dimensions are prone to several limitations which are addressed by scaling down the standard dimensions by 150× times (in terms of area requirement). Such switched capacitors are employed to develop phase shifters working in K-band (22 GHz) frequency range to yield appreciable performance both in terms of electromechanical and RF characterizations. Such switched capacitors are utilized to develop phase shifters which find immense applications in the design of Phased Array RADARs. Switched capacitors fabricated on 500 µm thick quartz substrates, result in 30° phase shift (0.66 mm × 1 mm in dimension) with associated minimum −0.18 dB insertion loss and better than −21 dB reflection coefficient at 22 GHz frequency. Electromechanical characterization reports an actuation voltage of 14.6 V, mechanical vibration frequency of 2.5 MHz and a switching time of 620 ns respectively. Demonstrations showing complete realization of 180° phase shifter (4 mm × 1 mm) employing a cascaded arrangement of six similar 30° unit cells are also included in this paper.     

火工装置轻量化小型化研究

为满足航天器轻量化对火工装置的需求,对火工装置轻量化小型化开展研究,重点探讨火工装置轻量化小型化原则、轻量化小型化途径以及实施轻量化小型化研制工作的基本流程。以某切割器为例,开展轻量化小型化研制,并进行极限功能裕度和极限强度裕度试验。结果表明,优化后的切割器重量和体积均减小50%,并且满足功能要求。     

Preparation and Evaluation of High Drug Content Particles

Abstract

To determine how to prepare high drug content particles using a Wurster fluidized bed to determine realizing the miniaturization of solid dosage forms, aspirin was selected as the model drug and granulated without any additive. In this study, the emphasis was on evaluating the key operation factors of airflow rate and atomizing flow volume. The properties of the resulting particles, such as the average diameter, particle strength, appearance, and compressibility using different airflow rates and atomizing flow volumes, were investigated. Furthermore, detailed optimization of the operation conditions was conducted by artificial neural network (ANN) analysis. The relationship between the controlling factors (powder supplied, concentration of spray liquid, the amount of consumed spray liquid, and spray rate) and the response variables (product yield, median diameter, angle of repose, and degradation of aspirin) was investigated after evaluating the airflow rate and atomizing flow volume effects. The resulting granules under optimum operation conditions showed excellent physicochemical properties such as particle size uniformity, flowability, and compressibility.     

MINIATURIZED MICROSTRIP BRANCH-LINE COUPLER WITH GOOD HARMONIC SUPPRESSION PERFORMANCE

This paper presents a miniaturized microstrip branch-line coupler with good harmonic suppression performance.The proposed coupler consists of four branch-line sections,each of which is loaded by open-c...     

Miniaturization of micrometric SiC from a detonation process of highly energetic material

Submicron- and, in a low quantity nano-sized carbide particles were successfully prepared through a dynamic process of energetic material detonation. For that, a commercial micrometric SiC powder, homogeneously coated by a polymer layer, was dispersed in an energetic 2,4,6-trinitrotoluene (TNT) matrix and then detonated. After detonation, the resulting carbide material was characterized by several techniques such as X-ray diffraction, infrared spectroscopy, electron microscopies, and nitrogen adsorption. The results showed a decrease in the initial micrometric SiC size with particle sizes reaching, in some cases, less than 20 nm. The specific surface area was also considerably increased since an approximate value of 7.8 m² g^− 1 was obtained for a detonated SiC sample as opposed to 0.12 m² g^− 1 for the initial micrometric SiC powder.     

片式元器件与SMT技术新进展

综述了片元器件与SMT技术的最新发展动态,重点讨论了现代信息产业全面促进电容类,电阻类,电感类片式元器件在体积微型化,结构复化等若干方面的新进展。     

小型智能测速仪的设计

介绍一种以 ＡＴ８９Ｃ２０５１单片机为核心,配上简单实用的外围电路构成的小型智能测速仪。它在设计上充分利用了单片机的内部资源和Ｉ／Ｏ口,基本上做到了最优化和最小化设计。     

Direct writing technology—Advances and developments

Direct writing (DW), also known as digital writing or digital printing, is a family of flexible multi-length scale processes for the deposition of functional materials to form simple linear or complex conformal structures on a substrate. This paper provides an overview of key DW technologies and their process characteristics under a unified classification system. In DW, a variety of mechanisms and energy modes such as inkjet, laser, mechanical pressure and tips are used to create material transfer to produce features from the nm to the mm range. This new group of additive on-demand processes complements existing manufacturing methods especially in product miniaturization and geometrical footprint reduction due to its conformal writing capability. The range of materials is exceptionally wide, ranging from metallics, ceramics, dielectrics and polymers to biomaterials. The thickness of the layer ranges from a monolayer of molecules to hundreds of micrometres. As DW is a scalable process, it is capable of high-throughput volume production, especially in microelectronics. Industrial applications have been expanding and numerous niche examples are given to illustrate meso-, micro- and nano-scale applications. Finally, challenges for its future development are also discussed.     

Miniaturized active stepped impedance planar inverted-F antenna using common ground

This paper presents a compact active integrated antenna (AIA) comprising of class-A power amplifier (PA) and stepped impedance planar inverted-F antenna (PIFA). In the proposed design, a common ground is used for both PA and PIFA, resulting a compact antenna of size 0.14λ₀ × 0.11λ₀ × 0.01λ₀ (λ₀ is free space wavelength at 0.85 GHz). Moreover, it is demonstrated that by using the stepped impedance radiator the operating frequency of the active PIFA is shifted down from its natural resonant frequency of 1.36 GHz to 0.85 GHz, offering an extensive size reduction of 80%. This active integration increases the passive antenna gain through the effective loading of the antenna to the power amplifier. The measured result indicates that the active and passive antennas achieved the gain of 15.7 dB and 3.81 dBi, respectively after the integration. In addition, the maximum SAR value of antenna is found to be 0.64 W/kg.     

中国MEMS的研究与开发进程

微机电系统（Micro Electro Mechanical Systems)是80年代发展起来的新兴交叉学科，其系统包括能源、微驱动器、微执行器、微传感器、微控制器以及与外界的接口等。由于该系统能够实现各类产品的微型化、集成化与便携化，因而在天上、地面和海洋的诸多领域有广泛的应用与产业前景。本文概括地介绍微机电系统学科的重大意义，13年来中国MEMS研发的总体概况，以及关注的热点。