scholarly journals Акустооптическая многолучевая аксиальная дифракция в парателлурите

2022 ◽  
Vol 48 (1) ◽  
pp. 43
Author(s):  
С.Н. Антонов ◽  
Ю.Г. Резвов ◽  
В.А. Подольский ◽  
О.Д. Сивкова
Keyword(s):  
Laser Radiation ◽  
Power Consumption ◽  
Frequency Response ◽  
Radiation Pattern ◽  
Crystal Size ◽  
Radio Signal ◽  
Single Frequency ◽  
Beam Radiation ◽  
Response Optimization ◽  
Angular Scanning

To form a multi-beam radiation pattern, it is proposed to use the axial geometry of acousto-optic interaction in paratellurite. In single frequency mode, the use of this geometry for angular scanning is characterized by a dip in the frequency response. Optimization of a multifrequency radio signal makes it possible to effectively divide laser radiation into several beams, while maintaining the fundamental advantages of axial geometry: minimum crystal size and power consumption

scholarly journals Through Wall Imaging Radar Antenna with a Focus on Opening New Research Avenues

2021 ◽  
Vol 71 (5) ◽  
pp. 670-681
Author(s):  
Krishnendu Raha ◽  
K. P. Ray
Keyword(s):  
Radiation Pattern ◽  
Review Paper ◽  
Single Frequency ◽  
Future Research ◽  
Scanning Angle ◽  
Imaging Radar ◽  
Requirements Specifications ◽  
New Research ◽  
Radar Antenna ◽  
Wall Imaging

This review paper is an effort to develop insight into the development in antennas for through wall imaging radar application. Review on literature on antennas for use in through wall imaging radar, fulfilling one or more requirements/specifications such as ultrawide bandwidth, stable and high gain, stable unidirectional radiation pattern, wide scanning angle, compactness ensuring portability and facilitating real-time efficient and simple imaging is presented. The review covers variants of Vivaldi, Bow tie, Horn, Spiral, Patch and Magneto-electric dipole antennas demonstrated as suitable antennas for the through wall imaging radar application. With an aim to open new research avenues for making better through wall imaging radar antenna, review on relevant compressive reflector antennas, surface integrated waveguide antennas, plasma antennas, metamaterial antennas and single frequency dynamically configurable meta-surface antennas are incorporated. The review paper brings out possibilities of designing an optimum through wall imaging radar antenna and prospects of future research on the antenna to improve radiation pattern and facilitate overall simple and efficient imaging by the through wall imaging radar.

Single-frequency erbium-doped fibre laser with random distributed feedback based on disordered structures produced by femtosecond laser radiation

2021 ◽  
Vol 51 (12) ◽  
pp. 1051-1055
Author(s):  
Mikhail Igorevich Skvortsov ◽  
S R Abdullina ◽  
Alexey Anatolyevich Wolf ◽  
A V Dostovalov ◽  
A E Churin ◽  
...  
Keyword(s):  
Laser Radiation ◽  
Femtosecond Laser ◽  
Distributed Feedback ◽  
Single Frequency ◽  
Fibre Laser ◽  
Femtosecond Laser Radiation ◽  
Disordered Structures ◽  
Erbium Doped

scholarly journals Considerations for the Design of UWB Antennas for Mobile and Consumer Equipment

2005 ◽  
Vol 1 (1) ◽  
pp. 1
Author(s):  
Dirk Manteuffel
Keyword(s):  
Radiation Pattern ◽  
Power Distribution ◽  
Ultra Wideband ◽  
Fdtd Simulation ◽  
Single Frequency ◽  
Frequency Dependency ◽  
Propagation Modeling ◽  
Antenna Performance ◽  
Received Power ◽  
The Impact

This paper presents some considerations on the design, characterization and optimization of UWB (Ultra WideBand) antennas for consumer communication equipment. As a first step a method to extract the spatio-temporal UWB antenna characterization from a FDTD simulation is given. Thereafter, the shape of a planar monopole is optimized to provide broadband matching. This is followed by the integration of latter antenna into a model of a DVD player and the impact of this integration on the antenna performance is evaluated. Finally, the transfer function of the complete system is extracted and used for indoor propagation modeling in an exemplary living home environment. The results show that the antenna integration into the DVD-chassis results into a directive radiation pattern that shows a significant frequency dependency. When this antenna is used for the propagation modeling, a single frequency ray-tracing simulation shows significant variation in the radiated power distribution in the room as a result of the directive pattern. When the received power is averaged over a larger bandwidth, the coverage becomes more smooth mainly due to the frequency dependency of the radiation pattern and frequency dependent propagation effects. Indeed, comparing the results of the integrated antenna to the case of the ideal isotropic radiator, no major disadvantages can be discerned anymore.

Weak, Stochastic Temporal Correlation of Large-Scale Synaptic Input Is a Major Determinant of Neuronal Bandwidth

2000 ◽  
Vol 12 (3) ◽  
pp. 693-707 ◽  
Author(s):  
David M. Halliday
Keyword(s):  
Frequency Response ◽  
Synaptic Input ◽  
Large Scale ◽  
Temporal Correlation ◽  
Spike Trains ◽  
Major Determinant ◽  
Single Frequency ◽  
Cell Simulation ◽  
Input Spike ◽  
Sample Pair

We determine the bandwidth of a model neurone to large-scale synaptic input by assessing the frequency response between the outputs of a two-cell simulation that share a percentage of the total synaptic input. For temporally uncorrelated inputs, a large percentage of common inputs are required before the output discharges of the two cells exhibit significant correlation. In contrast, a small percentage (5%) of the total synaptic input that involves stochastic spike trains that are weakly correlated over a broad range of frequencies exert a clear influence on the output discharge of both cells over this range of frequencies. Inputs that are weakly correlated at a single frequency induce correlation between the output discharges only at the frequency of correlation. The strength of temporal correlation required is sufficiently weak that analysis of a sample pair of input spike trains could fail to reveal the presence of correlated input. Weak temporal correlation between inputs is therefore a major determinant of the transmission to the output discharge of frequencies present in the spike discharges of presynaptic inputs, and therefore of neural bandwidth.

scholarly journals Balanced gain for a square metaloop antenna

2019 ◽  
Vol 6 ◽  
pp. 3
Author(s):  
Hisamatsu Nakano ◽  
Ittoku Yoshino ◽  
Tomoki Abe ◽  
Junji Yamauchi
Keyword(s):  
Frequency Response ◽  
Radiation Pattern ◽  
Free Space ◽  
Loop Antenna ◽  
Circularly Polarized ◽  
Left Handed ◽  
The Difference

A square loop antenna implemented using a metamaterial line, referred to as a metaloop, is discussed. The metaloop radiates a counter circularly polarized (CP) broadside beam when the loop circumference equals one guided wavelength. The frequency response of the gain shows two different maximum values: gain G Lmax for a left-handed CP wave at frequency fGLmax and gain GRmax for a right-handed CP wave at frequency fGRmax, where GLmax is smaller than GRmax. In order to increase GLmax, while not affecting the original GRmax as much as possible (i.e. balance the gain), a parasitic natural conducting loop (paraloop), whose circumference is one free-space wavelength at fGLmax, is placed at height Hpara above the metaloop. It is found that the difference in the gains can be reduced by choosing an appropriate Hpara. The radiation pattern at fGLmax is narrowed by the paraloop, while the VSWR is not remarkably affected.

Single-frequency fibre laser with a cavity formed by Bragg gratings written in the core of an active composite fibre using KrF laser radiation (248 nm)

2019 ◽  
Vol 49 (12) ◽  
pp. 1112-1116
Author(s):  
O N Egorova ◽  
O I Medvedkov ◽  
E S Seregin ◽  
S A Vasil'ev ◽  
S E Sverchkov ◽  
...  
Keyword(s):  
Laser Radiation ◽  
Bragg Gratings ◽  
Single Frequency ◽  
Fibre Laser ◽  
Composite Fibre ◽  
The Core ◽  
Krf Laser ◽  
Active Composite
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