Effect of the spatial dispersion on the propagation of electromagnetic waves in a magnetoplasma in the upper-hybrid frequency range

2003 ◽  
Author(s):  
A. Kostrov ◽  
G. Luchinin ◽  
G. Permitin ◽  
M. Starodubtsev
Keyword(s):  
Electromagnetic Waves ◽  
Spatial Dispersion ◽  
Frequency Range ◽  
Hybrid Frequency

The working standard of the unit of power of electromagnetic waves in the frequency range from 37,5 to 220 GHz

2020 ◽  
pp. 53-58
Author(s):  
A. V. Koudelny ◽  
I. M. Malay ◽  
V. A. Perepelkin ◽  
I. P. Chirkov
Keyword(s):  
Microwave Power ◽  
Electromagnetic Waves ◽  
Primary Standard ◽  
The State ◽  
Frequency Range ◽  
Working Standard ◽  
Extended Frequency Range ◽  
Effective Efficiency ◽  
Extended Frequency ◽  
Good Agreement

The possibility of using bolometric converters of microwave power from the State primary standard of the unit of power of electromagnetic waves in waveguide and coaxial paths GET 167-2017, which has a frequency range from 37,5 to 78,33 GHz, in an extended frequency range up to 220 GHz, is shown. Studies of semiconductor bolometric converters of microwave power in an extended frequency range have confirmed good agreement and smooth frequency characteristics of the effective efficiency factor of the converters. Based on the research results, the State working standard of the unit of power of electromagnetic waves of 0,1–10 mW in the frequency range from 37,5 to 220 GHz 3.1.ZZT.0288.2018 was approved. The technical characteristics of the working standard of the unit of power of electromagnetic oscillations in an extended frequency range from 37,5 to 220 GHz are given.

FORMATION OF A SCANNING ANTENNA BASED ON A HALF-WAVE DIPOLE

2021 ◽  
pp. 20-24
Author(s):  
С.М. Фёдоров ◽  
Е.А. Ищенко ◽  
И.А. Баранников ◽  
К.А. Бердников ◽  
В.В. Кузнецова
Keyword(s):  
Short Distance ◽  
Electromagnetic Waves ◽  
High Stability ◽  
Frequency Range ◽  
Current Position ◽  
Form Complex ◽  
Operating Frequency Range ◽  
Half Wave ◽  
Focus Radiation ◽  
Antenna Systems

Рассматривается полуволновый диполь с установленным рефлектором, который позволяет производить сканирование пространства с использованием вращения рефлектора вокруг диполя. Для полученной конструкции производилось моделирование основных параметров, которые показали высокую стабильность при различных положениях рефлектора, постоянное значение коэффициента направленного действия, ширины главного лепестка. Изменение направления излучения совпадает с текущим положением рефлектора. По сравнению с ситуацией, когда у антенны отсутствовал рефлектор, КНД антенны увеличился, так как произошла фокусировка электромагнитных волн. Коэффициент полезного действия и передне-заднее отношение сохраняют высокие значения во всем диапазоне рабочих частот. Применение предложенной конструкции позволяет упростить конструкцию сканирующих антенн, так как для ее реализации требуются лишь полуволновой диполь и плоский рефлектор, установленный на малом расстоянии от источника излучения. В процессе управления характеристиками требуется вращать рефлектор вокруг диполя, при этом диполь остается неподвижным, что позволяет повысить эффективность предложенной конструкции, так как не требуется формировать сложных антенных систем или устанавливать комбинацию из нескольких антенн для фокусировки излучения в одном направлении от источника The article discusses a half-wave dipole with an installed reflector, which allows scanning space using the rotation of the reflector around the dipole. For the resulting structure, we simulated the main parameters, which showed high stability at various positions of the reflector, a constant value of the directivity factor, and the width of the main lobe. The change in the direction of radiation coincides with the current position of the reflector. Compared to the situation when the antenna did not have a reflector, the directivity of the antenna increased since the focusing of electromagnetic waves took place. The efficiency and the front-to-back ratio remain high throughout the entire operating frequency range. The use of the proposed design makes it possible to simplify the design of scanning antennas since the implementation of the proposed design requires only a half-wave dipole and a flat reflector installed at a short distance from the radiation source. In the process of controlling the characteristics, it is required to rotate the reflector around the dipole, while the dipole remains stationary, which makes it possible to increase the efficiency of the proposed design, since it is not required to form complex antenna systems or install a combination of several antennas to focus radiation in one direction from the source

scholarly journals The Electromagnetic Wave Absorption Performance and Mechanical Properties of Cement-Based Composite Material Mixed with Functional Aggregates with High Fe2O3 and SiC

2021 ◽  
Vol 31 (4) ◽  
pp. 249-255
Author(s):  
Zuoqun Zhang ◽  
Chaoshan Yang ◽  
Hua Cheng ◽  
Xiaohan Huang ◽  
Yuhao Zhu
Keyword(s):  
Composite Material ◽  
Electromagnetic Wave ◽  
Electromagnetic Waves ◽  
Building Materials ◽  
Magnetic Loss ◽  
Frequency Range ◽  
Electromagnetic Wave Absorption ◽  
Wave Absorption ◽  
Test Board ◽  
Absorption Performance

Now there’re many researches on the electromagnetic radiation protection function of the cement-based electromagnetic wave absorbing materials, such materials have been widely used in various types of buildings. This paper proposed an idea for preparing a cement-based composite material by mixing functional aggregates with high content of Fe2O3 and SiC, that is, adding Fe3O4 powder and nano-SiC of different contents in the clay, and then sintering at 1190℃; the prepared aggregates showed obvious magnetic loss and dielectric loss to electromagnetic waves, and the numerical tube pressure could reach 16.83MPa. The double-layer reflectivity test board made of functional aggregates showed excellent electromagnetic wave absorption performance, its reflection loss was less than -10dB in the frequency range of 8~18GHz (corresponding to energy absorption greater than 90% EM), and its maximum RL reached -12.13dB. In addition, the compressive strength of the cement-based composite material at the age of 28 days reached 50.1 MPa, which can meet the strength requirements of building materials.

scholarly journals Observations of lower hybrid cavities in the inner magnetosphere by the Cluster and Viking satellites

2004 ◽  
Vol 22 (8) ◽  
pp. 2961-2972 ◽  
Author(s):  
A. Tjulin ◽  
M. André ◽  
A. I. Eriksson ◽  
M. Maksimovic
Keyword(s):  
Time Scales ◽  
Sounding Rocket ◽  
Lower Hybrid ◽  
High Altitudes ◽  
Frequency Range ◽  
General Shape ◽  
Lower Altitude ◽  
Inner Magnetosphere ◽  
Hybrid Frequency ◽  
The Individual

Abstract. Observations by the Viking and Cluster satellites at altitudes up to 35000km show that Lower Hybrid Cavities (LHCs) are common in the inner magnetosphere. LHCs are density depletions filled with waves in the lower hybrid frequency range. The LHCs have, until recently, only been found at altitudes up to 2000km. Statistics of the locations and general shape of the LHCs is performed to obtain an overview of some of their properties. In total, we have observed 166 LHCs on Viking during 27h of data, and 535 LHCs on Cluster during 87h of data. These LHCs are found at invariant latitudes from the auroral region to the plasmapause. A comparison with lower altitude observations shows that the LHC occurrence frequency does not scale with the flux tube radius, so that the LHCs are moderately rarer at high altitudes. This indicates that the individual LHCs do not reach from the ionosphere to 35000km altitude, which gives an upper bound for their length. The width of the LHCs perpendicular to the geomagnetic field at high altitudes is a few times the ion gyroradius, consistent with observations at low altitudes. The estimated depth of the density depletions vary with altitude, being larger at altitudes of 20000-35000km (Cluster, 10-20%), smaller around 1500-13000km (Viking and previous Freja results, a few percent) and again larger around 1000km (previous sounding rocket observations, 10-20%). The LHCs in the inner magnetosphere are situated in regions with background electrostatic hiss in the lower hybrid frequency range, consistent with investigations at low altitudes. Individual LHCs observed at high altitudes are stable at least on time scales of 0.2s (about the ion gyro period), which is consistent with previous results at lower altitudes, and observations by the four Cluster satellites show that the occurrence of LHCs in a region in space is a stable phenomenon, at least on time scales of an hour.

scholarly journals Cloaking using complementary media for electromagnetic waves

2019 ◽  
Vol 25 ◽  
pp. 29 ◽  
Author(s):  
Hoai-Minh Nguyen
Keyword(s):  
Refractive Index ◽  
Elliptic Equations ◽  
Electromagnetic Waves ◽  
Scientific Community ◽  
Maxwell Equations ◽  
Frequency Range ◽  
Negative Index Materials ◽  
Three Sphere ◽  
Weakly Coupled ◽  
Second Order Elliptic Equations

Negative index materials are artificial structures whose refractive index has negative value over some frequency range. The study of these materials has attracted a lot of attention in the scientific community not only because of their many potential interesting applications but also because of challenges in understanding their intriguing properties due to the sign-changing coefficients in equations describing their properties. In this paper, we establish cloaking using complementary media for electromagnetic waves. This confirms and extends the suggestions of Lai et al. [Phys. Rev. Lett. 102 (2009) 093901] for the full Maxwell equations. The analysis is based on the reflecting and removing localized singularity techniques, three-sphere inequalities, and the fact that the Maxwell equations can be reduced to a weakly coupled second order elliptic equations.

Parametric Analysis of an Optical Log-Spiral Nano-Antenna for Infrared Energy Harvesting

2020 ◽  
Vol 35 (10) ◽  
pp. 1183-1191
Author(s):  
Abdulrahman Alhomrani ◽  
Ali Yahyaoui ◽  
Anas Al Hashmi ◽  
Ameni Mersani ◽  
Majed Nour ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Electric Field ◽  
Electromagnetic Waves ◽  
Substrate Thickness ◽  
Frequency Range ◽  
Initial Angle ◽  
Spiral Antenna ◽  
Incident Wave Angle ◽  
Maximum Electric Field ◽  
Wave Angle

In this paper, we present the design of a spiral nano-antenna dedicated to infrared energy harvesting at 28.3 THz. A comprehensive, detailed parametric study of key parameters such as the initial angle at the origin arm, width of the spiral arms, gap between the two arms, thickness of substrate, length of substrate, thickness of patch and number of turns of the nano-antenna is also presented and discussed in order to harvest maximum electric field in the gap of the spiral antenna in the frequency range of 28 – 29 THz. The maximum electric field is simulated at 28.1, 28.3, 28.5 and 28.7 THz. A variation of the electric field of the antenna for different value of incident wave angle at the resonance frequency 28.3 THz has been simulated. The main advantages of the studied structure are its ability to reach high confined electric field within its gap, its wideband behavior around the operating frequency 28.3 THz, and its insensitivity to polarization of incident electromagnetic waves.

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