scholarly journals Low-Profile Metamaterial-Based Adaptative Beamforming Techniques

2020 ◽  
Author(s):  
Chung-Tse Michael Wu ◽  
Pai-Yen Chen
Keyword(s):  
Beam Steering ◽  
Smart Antennas ◽  
Spatial Multiplexing ◽  
Basic Principles ◽  
Practical Applications ◽  
Critical Comparison ◽  
Low Profile ◽  
Radiation Properties ◽  
Millimeter Wave Range ◽  
Wave Range

In this chapter, we will review recent research advances on beamforming and spatial multiplexing techniques using reconfigurable metamaterials (MTMs) and metasurfaces. This chapter starts by discussing basic principles and practical applications of transmission line-based metamaterials and planar metasurfaces, followed by their active versions that enable novel smart antennas with beam steering and beamshaping functions. We include detailed descriptions of their practical realizations and the integration with circuits and the radio-frequency (RF) frontend, which are used to adaptively and dynamically manipulate electromagnetic radiation. We summarize the state-of-the-art MTM/metasurface-based beamforming techniques and provide a critical comparison for their uses in the RF-to-millimeter-wave range in terms of cost, reconfigurability, system integratability and radiation properties. These techniques are expected to pave the way for the massive deployment of communication, radar, remote sensing and medical and security imaging systems.

Toxicology

2017 ◽  
Author(s):  
Robert Laumbach ◽  
Michael Gochfeld
Keyword(s):  
Molecular Mechanisms ◽  
Molecular Targets ◽  
Toxicity Testing ◽  
The Body ◽  
Toxic Substances ◽  
Basic Principles ◽  
Practical Applications ◽  
Mechanisms Of Toxicity ◽  
Body Distribution ◽  
Threshold Doses

This chapter describes the basic principles of toxicology and their application to occupational and environmental health. Topics covered include pathways that toxic substances may take from sources in the environment to molecular targets in the cells of the body where toxic effects occur. These pathways include routes of exposure, absorption into the body, distribution to organs and tissues, metabolism, storage, and excretion. The various types of toxicological endpoints are discussed, along with the concepts of dose-response relationships, threshold doses, and the basis of interindividual differences and interspecies differences in response to exposure to toxic substances. The diversity of cellular and molecular mechanisms of toxicity, including enzyme induction and inhibition, oxidative stress, mutagenesis, carcinogenesis, and teratogenesis, are discussed and the chapter concludes with examples of practical applications in clinical evaluation and in toxicity testing.

scholarly journals A Review on the Development of Rotman Lens Antenna

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Shruti Vashist ◽  
M. K. Soni ◽  
P. K. Singhal
Keyword(s):  
High Performance ◽  
Beam Steering ◽  
Phase Error ◽  
Antenna System ◽  
Surveillance Systems ◽  
Electronic Warfare ◽  
Design Concepts ◽  
Low Profile ◽  
True Time ◽  
The One

Rotman lenses are the beguiling devices used by the beamforming networks (BFNs). These lenses are generally used in the radar surveillance systems to see targets in multiple directions due to its multibeam capability without physically moving the antenna system. Now a days these lenses are being integrated into many radars and electronic warfare systems around the world. The antenna should be capable of producing multiple beams which can be steered without changing the orientation of the antenna. Microwave lenses are the one who support low-phase error, wideband, and wide-angle scanning. They are the true time delay (TTD) devices producing frequency independent beam steering. The emerging printed lenses in recent years have facilitated the advancement of designing high performance but low-profile, light-weight, and small-size and networks (BFNs). This paper will review and analyze various design concepts used over the years to improve the scanning capability of the lens developed by various researchers.

Multiple-ray passive radiovision systems of millimeter-wave range

1999 ◽  
Author(s):  
Valeri V. Gladun ◽  
Yuri A. Pirogov ◽  
Vladimir S. Ivanov ◽  
Dmitri A. Tischenko ◽  
Evgeni N. Terentiev
Keyword(s):  
Millimeter Wave ◽  
Millimeter Wave Range ◽  
Wave Range

scholarly journals Solar Flash Sub-Millimeter Wave Range Spectrum Part Radiation Modeling

2014 ◽  
Vol 15 (09) ◽  
Author(s):  
Vladimir Shustikov ◽  
Andrey Shumov ◽  
Yuri Tcap ◽  
Nadezhda Jarkova ◽  
Alexander Morgachev ◽  
...  
Keyword(s):  
Millimeter Wave ◽  
Millimeter Wave Range ◽  
Wave Range ◽  
Radiation Modeling

scholarly journals Effect of Bi2O3-B2O3 as a Sintering aid in Microstructure and Dielectric Properties of Fe2Mo3O12 Electroceramic.

2020 ◽  
Author(s):  
Eduardo Araújo ◽  
Marcelo Silva ◽  
Mauricio Pereira ◽  
Antonio Sombra ◽  
Igor Vasconcelos ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Sintering Process ◽  
Nyquist Diagram ◽  
Electron Microscopic ◽  
Sintering Aid ◽  
Low Dielectric ◽  
Low Thermal Expansion ◽  
Millimeter Wave Range ◽  
Wave Range ◽  
Low Permittivity

Abstract Molybdates from A2Mo3O12 family have been widely investigated due to its low sintering temperature, low thermal expansion coefficient, and low dielectric loss. Fe2Mo3O12 (FMO) is an oxide from this family and widely used in the catalytic field. The aim of this work is to evaluate the influence of the Bi2O3-B2O3 as a sintering aid in the microstructure and dielectric properties of FMO. The diffraction results showed that the FMO with the monoclinic structure phase was obtained after the calcination process (650 °C). Mössbauer spectroscopy showed the formation of Fe2O3 after the sintering process at 800 °C. The scanning electron-microscopic demonstrates an increase of the grain as a function of sintering aid concentration. The samples were analyzed by using the impedance spectroscopy at radiofrequency with temperature variation. The Nyquist diagram obtained in this temperature range was fitted from an equivalent circuit with three R-CPE associations, corresponding to the morphology of the electroceramics. For dielectric properties in the microwave, all the samples showed values of εr lower than 10. Values of Q x f above 14132.35 GHz were achieved. The thermal stability was evaluated by the temperature coefficient of resonant frequency (τf). The lowest τf values of -6.55 ppm/°C and -4.35 ppm/°C (near-zero) were measured to FMO and FMO mixed with 7.5 wt% Bi2O3-B2O3, respectively. Based on these results, FMO can be used to low permittivity ceramic for low temperature co-fired ceramics (LTCC) applications, antenna substrate, and millimeter-wave range.

The Results of Astroclimate Observations in the Short-Wave Length Interval of the Millimeter-Wave Range on the Suffa Plateau

2017 ◽  
Vol 59 (8-9) ◽  
pp. 763-771 ◽  
Author(s):  
G. M. Bubnov ◽  
Yu. N. Artemenko ◽  
V. F. Vdovin ◽  
D. B. Danilevsky ◽  
I. I. Zinchenko ◽  
...  
Keyword(s):  
Millimeter Wave ◽  
Wave Length ◽  
Short Wave ◽  
Short Wave Length ◽  
Millimeter Wave Range ◽  
Wave Range

Backscattered intensity from model atmospheric ice crystals in the millimeter-wave range

2001 ◽  
Vol 40 (30) ◽  
pp. 5337 ◽  
Author(s):  
Rosalba Saija ◽  
Maria A. Iatì ◽  
Paolo Denti ◽  
Ferdinando Borghese ◽  
Orazio I. Sindoni
Keyword(s):  
Millimeter Wave ◽  
Ice Crystals ◽  
Millimeter Wave Range ◽  
Wave Range
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