Kamaljit Rangra

Bio: Kamaljit Rangra is an academic researcher from Indian Institute of Technology, Jodhpur. The author has contributed to research in topics: Insertion loss & Capacitive sensing. The author has an hindex of 11, co-authored 80 publications receiving 511 citations. Previous affiliations of Kamaljit Rangra include University of Trento & The National Academy of Sciences, India.

A novel interdigitated, inductively tuned, capacitive shunt RF — MEMS switch for X and K bands applications

Abstract: This paper presents a new type of capacitive shunt RF-MEMS switch. In the proposed design, interdigitation of signal lines with actuation electrodes is used to make a compact device. A bridge structure anchored in between ground planes and attached to two cantilevers on either side has been used to implement the switch structure. This novel structure is used to inductively tune the isolation peaks in X and K bands which is not possible with conventional approach. The designed switch shows an insertion loss of 0.01 dB to 0.11 dB over the frequency range from 1 to 25 GHz. Isolation of 34.71, 34.33, and 40.7 dB has been observed at 10.4 GHz, 11 GHz and 21.4 GHz when bridge is electro-statically actuated with either left, right or both cantilevers in the down state respectively. The bridge structure shows a pull-in voltage of 12.25 V and switching time of 34.40 μs whereas left and right cantilevers have 7.5 V and 57 μs. The designed device can be useful for the future multiband communication applications.

Design and Development of a Double-Bridge Micromirror With Bending and Twisting Cantilevers for Multiobject Spectroscopy

Abstract: This article presents the design, development, and characterization of a double-bridge electrostatically actuated micromirror for multiobject spectroscopy (MOS). The proposed structure is an improvement over single-bridge micromirrors in terms of aperture size, pull-in voltage, degrees of freedom, and fill factor. The two-axis symmetric rotation mechanism of the proposed micromirror is achieved by bending and twisting action of the suspended cantilevers which is contrary to the twisting cantilevers of a conventional one-axis torsional micromirror. The placement of anchor and cantilevers under the mirror plate results in a high fill factor when arranged in a 2-D array. The analytical modeling, design optimization, and static and dynamic analysis are done using finite-element method (FEM) in Coventorware. An optimized design is fabricated using a simple approach of surface micromachining and electroplating. For a micromirror of size $200\,\,\mu \text{m}\,\,\times 200\,\,\mu \text{m}$ and the actuation gap of $2.5~\mu \text{m}$ , the device exhibits a tilt angle of 1.5° at a pull-in voltage of 23.1 V, a switching time of $38~\mu \text{s}$ , and the resonance frequency of 35.23 kHz. A ${3} \times {3}$ array of the micromirror is demonstrated with a fill factor of more than 95%. The deflection range can be increased by simply increasing the thickness of the sacrificial layer and without any major process modification.

Impact of post deposition annealing in O2 ambient on structural properties of nanocrystalline hafnium oxide thin film

Abstract: In the present work, HfO2 thin film (100nm) has been deposited by sputtering technique and annealed at various temperatures ranging from 400 to 1000\degree (in step of 200 \degree) in O2 ambient for 10 min. The samples have been characterized using XRD, FTIR, EDAX, AFM and Laser Ellipsometer. The impact of annealing temperatures in O2 ambient on structural properties such as crystallite size, phase, orientation, stress have been studied using XRD. The Hf-O phonon peaks in the infrared absorption spectrum are detected at 512, 412 cm^-1 . The stretching vibration modes at 720 cm^-1 and 748 cm^-1 correspond to HfO2. AFM data show mean grain size in the range of 38 nm to 67 nm. The film reveals variation in structural properties, which appears to be responsible for variation in oxygen percentage, refractive index (1.96 to 2.01) at 632 nm wavelength and roughness (6.13nm to 16.40nm). Annealing temperature as well as ambient condition has significant effects on stress, crystal size and thus the arrangement of atoms. For good quality film, annealing temperature larger than 600 \degree is desired.

RF MEMS compact T-type switch design for switch matrix applications in space telecommunication

Abstract: This paper presents a novel approach to monolithically implement a planar multiport radio-frequency (RF) microelectromechanical systems (MEMS) T-type switch. T-type switches are used as building blocks of redundancy switch matrices used in space telecommunication. The T-type switch performs signal routing in three operational states. Two of them are boundary states while the other one is a crossover state. The proposed design uses a series metal contact clamped-clamped beam SPST switches, four port psi junctions and a RF crossover. The simulated results for the entire T-type switch demonstrate an insertion loss of −0.48dB and isolation better than −22.12dB for all states for frequencies up to 25GHz. The use of eight switches instead of twelve makes T-type switch compact. This improves the reliability and compactness of the redundancy switch matrix. The switch gives excellent RF performance near X-band and Ku-band which is the most widely used frequency range for satellite communication.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Sub-10 nm electron beam lithography using cold development of poly(methylmethacrylate)

Abstract: We investigate poly(methylmethacrylate) (PMMA) development processing with cold developers (4–10 °C) for its effect on resolution, resist residue, and pattern quality of sub-10 nm electron beam lithography (EBL). We find that low-temperature development results in higher EBL resolution and improved feature quality. PMMA trenches of 4–8 nm are obtained reproducibly at 30 kV using cold development. Fabrication of single-particle-width Au nanoparticle lines was performed by lift-off. We discuss key factors for formation of PMMA trenches at the sub-10 nm scale.

What is Design and Technology

Abstract: Design and technology is an inspiring, rigorous and practical subject. Using creativity and imagination, pupils design and make products that solve real and relevant problems within a variety of contexts, considering their own and others’ needs, wants and values. They acquire a broad range of subject knowledge and draw on disciplines such as mathematics, science, engineering, computing and art. Pupils learn how to take risks, becoming resourceful, innovative, enterprising and capable citizens. Through the evaluation of past and present design and technology, they develop a critical understanding of its impact on daily life and the wider world. High-quality design and technology education makes an essential contribution to the creativity, culture, wealth and well-being of the nation.