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Wyszukujesz frazę "41.20.Jb" wg kryterium: Temat


Tytuł:
On Electromagnetic-Acoustic Analogies in Energetic Relations for Waves Interacting with Material Surfaces
Autorzy:
Dukata, A.
Kapelewski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1811519.pdf
Data publikacji:
2008-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
41.20.Jb
Opis:
In the paper we consider propagation of a monochromatic surface electromagnetic field at the interface separating two semi-infinite media - a metamaterial (generally with complex permittivity and permeability) and a conventional dielectric medium. The metamaterial is treated as homogeneous and isotropic (it is so-called effective medium approximation). It is true for e.g. artificial metamaterials with negative dielectric permittivity and negative permeability in the microwave frequency range. The last materials are known as left handed and a conventional as right handed media. In this work the classical optical theorem is extended to the case of scattering of electromagnetic surface waves incident at the interface separating a left handed medium and a right handed dielectric medium. The analogous theorem is known in the scattering theory for elastic fields.
Źródło:
Acta Physica Polonica A; 2008, 114, 6A; A-69-A-73
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Polaritonic Microwave Waves of Inclined Incidence in Some Magnetodielectric Superlattices
Autorzy:
Kapelewski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1417967.pdf
Data publikacji:
2012-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
41.20.Jb
Opis:
This paper concerns a theoretical study of microwave phonon-polaritons excited in a planar magneto-dielectric composite by a plane electromagnetic wave obliquely incident on its surface. The composite consists of alternately spaced piezoelectric and piezomagnetic layers having transverse isotropic properties for both electromagnetic and elastic parameters. Results include direction-dependent dispersion for phase velocity of phonon-polariton modes being excited by the incident electromagnetic wave in the superlattice in consideration here. A peculiar kind of coupling is proved to appear in the system treated, which do not exist in the case of electromagnetic waves propagating along principal symmetry axes. The paper concludes with a short review of available literature data on current and prospective applications of the microwave polaritons.
Źródło:
Acta Physica Polonica A; 2012, 122, 5; 833-836
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Material Analysis and Application for Radio Frequency Electromagnetic Wave Shielding
Autorzy:
Yener, S.
Cerezci, O.
Powiązania:
https://bibliotekanauki.pl/articles/1187407.pdf
Data publikacji:
2016-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
41.20.Gz
41.20.Jb
Opis:
Our environment is full of radio frequency (RF) electromagnetic radiation due to rapid progress of wireless communication technologies, which have many applications, such as base stations of mobile communication networks and wireless internet antennas. In the context of Electromagnetic Compatibility (EMC) discipline, the word shield is used to describe any sort of metal sheet or material capable of reflecting, refracting or absorbing electromagnetic radiation (EMR), which is custom manufactured for the target electronic device casing, in a way to intervene any radiation passing to and from the device. Examining of electromagnetic shielding effectiveness (SE) is an important part of not only ensuring electromagnetic compatibility and of protecting electrical and electronic equipment but also protection of human beings against electromagnetic energy exposure as well. In this study, after a brief introduction and review on electromagnetic shielding, material selection and their applications for an indoor environment protection against electromagnetic radiation are explained. Potential electromagnetic shielding values of fabrics found in the market have been analyzed and compared by considering various criteria and requirements. Experimental results show that around 20 dB shielding effectiveness values can be obtained using test fabrics for a typical indoor environment.
Źródło:
Acta Physica Polonica A; 2016, 129, 4; 635-638
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Solid State Plasma in the Pulse Modulated Magnetic Field
Autorzy:
Jankauskas, Z.
Barauskas, S.
Kvedaras, V.
Powiązania:
https://bibliotekanauki.pl/articles/1807893.pdf
Data publikacji:
2009-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
40.41.Cr
41.20.Jb
Opis:
Radio frequency (RF) magnetoplasmic waves known as helicons will propagate in solid-state plasma of semiconductors when a strong magnetic field is applied. Helicons have an exact analogy with an electromagnetic whistler wave which is frequently propagated in the low density plasma of the Earth ionosphere. In our experiments the modulated magnetic field is being used for excitation of helicons. It is shown that in the case of pulse modulated field along with the RF helicon waves the transient cyclotron frequency oscillations exist in the semiconductor plasma. For observation of the cyclotron radiation frequency $ω_c$ the modulation depth about one percent is sufficient. The measurement of $ω_c$ provides an opportunity to determine the masses of electrons and holes in solid-state plasma of semiconductors. In already existing method the absorption of electromagnetic radiation on the cyclotron frequency is being used. For this case it is necessary to have an external infrared generator. In our method the cyclotron radiation is being generated by electrons (or holes) directly and additional external excitation is not needed.
Źródło:
Acta Physica Polonica A; 2009, 115, 6; 1025-1027
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Negative Refraction as a Source of Some Pedagogical Problems
Autorzy:
Veselago, V.
Powiązania:
https://bibliotekanauki.pl/articles/1814051.pdf
Data publikacji:
2007-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.Ci
41.20.Jb
Opis:
The appearance of material with negative values of dielectric and magnetic permeabilities ε and μ and with negative index of refraction n forces to revise the accustomed forms of some well-known formulae of electrodynamics. This is connected with fact, that these correlations in repressing majority of sources is written in tacit suggestion that magnetic permeability of most of materials is μ=1, factor of refraction n=ε and is undoubtedly executed the correlation n > 0. Such approach could be named as "nonmagnetic". However, if n <0, this nonmagnetic approach can bring very hard mistakes.
Źródło:
Acta Physica Polonica A; 2007, 112, 5; 777-781
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acousto-Electromagnetic Analogies in Diffraction Phenomena Occurring in the Semi-Infinite Cylindrical Waveguide
Autorzy:
Snakowska, A.
Powiązania:
https://bibliotekanauki.pl/articles/1807756.pdf
Data publikacji:
2009-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
41.20.Jb
43.20.Wd
Opis:
The paper presents analogies between acoustic and electromagnetic wave field occurring in limited areas, such as waveguides, when electromagnetic waves are not purely transversal. The acousto-electromagnetic analogies exist in structures such as plane, rectangular or cylindrical infinite waveguides, if the fields are analysed by means of potentials - the velocity potential for sound waves and the Hertz potentials for electromagnetic waves. It has been demonstrated why these analogies between the potentials representing solutions of the wave equation with adequate boundary conditions and expressed as sums of admissible duct modes do fail, in general, for the semi-infinite cylindrical duct, and why they remain valid when the propagating electromagnetic mode is axisymmetric.
Źródło:
Acta Physica Polonica A; 2009, 116, 3; 410-413
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
TE Surface Waves in a Plasma Sandwich Structure
Autorzy:
Shaikh, M.
Zamir, B.
Ali, R.
Powiązania:
https://bibliotekanauki.pl/articles/1189881.pdf
Data publikacji:
2015-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
41.20.Jb
84.40.Az
Opis:
Transverse electric surface waves are analyzed in a plasma medium bounded by a left-handed material. A dispersion relation is obtained by applying the boundary conditions for the tangential field components. Numerical investigations show the dependence of effective wave index on the propagation frequency for different thicknesses and number densities of the plasma medium and also for different values of the filling factor of left-handed material.
Źródło:
Acta Physica Polonica A; 2015, 127, 6; 1625-1629
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Consequences of Unit Cell Design in Metamaterial Perfect Absorbers
Autorzy:
Bagci, F.
Akaoglu, B.
Powiązania:
https://bibliotekanauki.pl/articles/1398784.pdf
Data publikacji:
2016-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Xj
41.20.Jb
Opis:
Metamaterials are a new class of composite materials with unusual properties that allow controlling of electromagnetic waves by properly engineering the response functions, which are not observed in constituent materials. However, since absorption of metamaterials is mainly based on electromagnetic resonances, the operating bandwidth is relatively narrow. Utilization of more than a single metallic structure with different geometrical parameters in each unit cell is a common way of accomplishing multiple band and/or broadband absorption. There are two usual approaches for this purpose: (a) multilayer unit cell design where metallic structures on dielectric substrate are stacked one on top of the other; (b) side by side unit cell design where metallic structures are distributed on a dielectric substrate. However, to the best of our knowledge, these two different approaches are not comparatively investigated. In this study, we propose metamaterial-based perfect absorbers with two different unit cell designs and simulate transmittances, reflectances and absorbances for each design by a commercial electromagnetic solver, CST Microwave Studio. It is found that each design has its own advantages in terms of device thickness, absorption bandwidth and angular dependence, which might be severely important for particular purposes.
Źródło:
Acta Physica Polonica A; 2016, 129, 4; 792-796
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Yearly, Seasonal and Daily Variations of Radio Refractivity
Autorzy:
Žilinskas, M.
Tamošiūnas, S.
Tamošiūnaitė, M.
Tamošiūnienė, M.
Powiązania:
https://bibliotekanauki.pl/articles/1505233.pdf
Data publikacji:
2011-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
84.40.-x
41.20.Jb
Opis:
Yearly, seasonal and daily variations of radio refractivity have been analyzed. The method proposed in the recommendation of International Telecommunication Union ITU has been used. The local meteorological data have been used in calculation of radio refractivity. The highest values of the radio refractivity have been observed in Klaipėda (in Seacoast) in the year 2009. In July, the values of the radio refractivity were highest in all localities investigated here and over all the time of the day in the year 2009. In the continental part of Lithuania (in Vilnius and Kaunas), analysis of radio refractivity has been made by using the meteorological data of longer period (starting from April 2005 up to July 2010). Five-year meteorological data collected in February, April, July and October have been used. It was obtained that the values of refractivity in the year 2010 are much higher than ones obtained in all the years of the period investigated here.
Źródło:
Acta Physica Polonica A; 2011, 119, 4; 533-536
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Insight into Coherent Backscattering Evaluation Techniques of Prospective Use in High Frequency Polarimetric Radar Image Processing
Autorzy:
Kapelewski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1506794.pdf
Data publikacji:
2010-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
41.20.Jb
03.50.De
Opis:
Coherence in multiple scattering is important as it applies to imaging and detection of object in multiple scattering environments. These phenomena may also be used to investigate images of objects obscured by them. The scattering observations using very rough surfaces can provide useful insight into their statistic as they lie outside the range of validity of the standard theories. Recently, there has been growing interest in the phenomenon of backscattering enhancement in the reflection of electromagnetic waves of mm wave range from both atmospheric hydrometeors (rain, snow and precipitation) as well as very rough surfaces (including that of sea and terrain sea). Strong backscattering enhancement of mm waves incident at different incident angles, both in the TE and TM polarizations, was observed experimentally. In the paper a short description of specific techniques used for treating image processing of strongly irregular media is shortly presented. An emphasis is placed on the phenomena of interest in advanced polarimetric radar especially in mm wave range.
Źródło:
Acta Physica Polonica A; 2010, 118, 6; 1161-1167
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of Electromagnetic Emitter Position from Passive Radar Bearings as Linear Least Squares Problem
Autorzy:
Kawalec, A.
Kojdecki, M.
Wajszczyk, B.
Powiązania:
https://bibliotekanauki.pl/articles/1506796.pdf
Data publikacji:
2010-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
41.20.Jb
03.50.De
Opis:
Mathematical formulation of an inverse problem of radiolocation is discussed. Determination of electromagnetic emitter position from passive radar bearings is transformed into a linear least squares problem and equivalent system of normal equations. Eventually spatial localisation of emitter is reduced to solving system of linear algebraic equations with entries of coefficient matrix and free term depending on bearings in a nonlinear way. Regularisation algorithm is proposed.
Źródło:
Acta Physica Polonica A; 2010, 118, 6; 1171-1173
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exact Phase and its Eikonal Approximation for Class of Reflectionless Index Profiles
Autorzy:
Sharma, S. K.
Ghosh, G.
Powiązania:
https://bibliotekanauki.pl/articles/1963260.pdf
Data publikacji:
1997-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.25.Fx
41.20.Jb
Opis:
We examine the problem of transmission of electromagnetic waves in a multiparameter reflectionless dielectric. It is shown that it is possible to obtain an analytic form for the phase of the exact transmission amplitude. In the high frequency limit the exact result is found to lead to the eikonal approximation. Interestingly, the high frequency limit and long-range approximation required for the validity of the eikonal approximation are not independent here.
Źródło:
Acta Physica Polonica A; 1997, 91, 3; 555-561
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Numerical Synthesis of a Radar Signal Having Required Autocorrelation Function
Autorzy:
Leśnik, Cz.
Kawalec, A.
Szugajew, M.
Powiązania:
https://bibliotekanauki.pl/articles/1506803.pdf
Data publikacji:
2010-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
41.20.Jb
03.50.De
Opis:
This paper presents the problem of synthesis of signals modulated in frequency with autocorrelation function that implements an optimal approximation to a given autocorrelation function. After theoretical introduction an algorithm of frequency modulated signal synthesis is presented. Simulation results made in Matlab are presented in the last section.
Źródło:
Acta Physica Polonica A; 2010, 118, 6; 1194-1198
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of Electromagnetic Wave Absorber Based on Carbon Fiber Reinforced Aerated Concrete Using Time-Domain Method
Autorzy:
Laukaitis, A.
Sinica, M.
Balevičius, S.
Levitas, B.
Powiązania:
https://bibliotekanauki.pl/articles/1813404.pdf
Data publikacji:
2008-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
41.20.Jb
81.05.Uw
Opis:
The electromagnetic wave absorbers prepared from autoclaved aerated concrete containing carbon fibers as additions in the shape of slabs with pyramids cut on one plane of these slabs were tested using dc microwave source and the time-domain method. It was demonstrated that autoclaved aerated concrete allows one to fabricate electromagnetic wave absorbers which have a reflection coefficient up to -30 dB in the frequency range from 2 GHz to 18 GHz.
Źródło:
Acta Physica Polonica A; 2008, 113, 3; 1047-1050
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sharp-rejection, wide and deep stopband low pass filter design using open stubs and DGS patterns
Autorzy:
Challal, M.
Boulakroune, M.
Powiązania:
https://bibliotekanauki.pl/articles/1061519.pdf
Data publikacji:
2016-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
41.20.-q
41.20.Jb
11.10.-z
Opis:
A sharp rejection, wide and deep stopband microstrip low pass filter is investigated in this paper. The proposed low pass filter is composed of three defected ground structure patterns and four open stubs. Simulated results verify that the filter has a sharpness factor of 0.9, a low insertion loss of 0.65 and a return loss less than 15 dB. Moreover, a wide stopband at 20 dB rejection ranging from 4.55 GHz to 11.62 GHz is accomplished. The filter presented in this work was compared with the previous works completed on low pass filter with sharp rejection. It has shown that the filter provides good performances in terms of sharp rejection, wide and deep rejection band and small passband insertion loss compared to those reported in the literatures.
Źródło:
Acta Physica Polonica A; 2016, 130, 1; 9-10
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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