Calculation of Electromagnetic Scattering from a Pruppacher-Pitter Raindrop Using M.A.S. and Slant Path Rain AttenuationPrediction
28 Nov 2005-International Journal of Infrared and Millimeter Waves (Kluwer Academic Publishers-Plenum Publishers)-Vol. 26, Iss: 12, pp 1783-1802
TL;DR: In this article, the scattering of a plane electromagnetic wave from a Pruppacher-Pitter raindrop is treated using the Method of Auxiliary Sources (MAS) and compared with those taken from the open literature -in the form of real and imaginary part of the forward scattering amplitude -with excellent results.
Abstract: The combined effects of hydrometeor scattering and absorption result in significant power loss, for Earth-space microwave links operating at frequencies above 10GHz. With the increasing deployment of higher frequencies in commercial wireless networks, the accurate estimation of the specific rain attenuation is very significant for the reliable design of a radio communication system. In the present paper, the scattering of a plane electromagnetic wave from a Pruppacher-Pitter raindrop is treated using the Method of Auxiliary Sources (MAS). The obtained data are compared with those taken from the open literature -in the form of real and imaginary part of the forward scattering amplitude - with excellent results. Then, they are used for the numerical calculation of both the specific rain attenuation and the exceedance probability function, in the case of a hypothetical satellite link located in various climatic regions. The comparison with other models against experimental data has given very encouragingresults.
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TL;DR: A new dynamic power allocation algorithm is proposed the novelty of which lies in treating users with similar power requirement as a group, instead of individuals, to serve more number of users than the existing technique.
Abstract: For multi-beam broadband satellites operating at 10 GHz and above frequencies, rain attenuation is the dominant impairment factor. Using a stochastic model for rain attenuation prediction and a greedy approach, dynamic power allocation has been recently shown to increase the number of users served than the static technique. This letter proposes a new dynamic power allocation algorithm the novelty of which lies in treating users with similar power requirement as a group, instead of individuals. Thus, without resorting to exhaustive search we are able to serve more number of users than the existing technique.
25 citations
Cites background or methods from "Calculation of Electromagnetic Scat..."
...The initial value for Ar,ij(t) can be evaluated using the relation [3],[5]:...
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...a5 (the constants of Garcia-Lopez Model [8]) and Lreal - the equivalent path length [8] can be found using the methodology described in [5]....
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...76, a4 = 307, a5 = 8000 while Lreal was latitude dependent and was found using the methodology described in [5]....
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...a5 were obtained using [5] and came out to be a1 = 0....
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TL;DR: In this article, a regression fitting analysis in combination with the Method of Auxiliary Sources (MAS) is implemented for the calculation of the scattering amplitude of a plane electromagnetic wave by a Pruppacher-Pitter raindrop.
Abstract: Millimeter waves propagating through the atmosphere experience absorption and dispersion due to various physical mechanisms. Gaseous oxygen, water vapor and suspended water droplets represent the principal absorbers in moist air, while in the presence of rain additional phenomena of absorption and scattering further degrade the transmitted signal. The scope of this paper is the incorporation of rainfall rate effects on pulse propagation along Line-Of-Sight (LOS) Fixed Wireless Access (FWA) paths. A regression fitting analysis in combination with the Method of Auxiliary Sources (MAS) is implemented for the calculation of the scattering amplitude of a plane electromagnetic wave by a Pruppacher-Pitter raindrop. As a result, analytical expressions of rain-influenced propagation factors are derived. Numerical results for horizontally and vertically polarized channels are presented and some important conclusions are derived.
22 citations
Cites background from "Calculation of Electromagnetic Scat..."
...350 cm and frequencies 10 to 60 GHz [9]....
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...(MAS) to the problem of electromagnetic scattering by a distorted, not spherical raindrop [9]....
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20 Nov 2014
TL;DR: In this paper, numerical analysis of RCS calculations for ellipsoidal drops and Pruppacher-Pitter drops by using spherical drops and dipole scattering approximations are considered.
Abstract: The numerical analysis of RCS calculations for ellipsoidal drops and Pruppacher-Pitter drops by using spherical drops and dipole scattering approximations are considered. The results are compared with the data of exact solution of the diffraction problem of electromagnetic scattering on such drops by using the method of moments for horizontal and vertical polarization of an incident field at wavelengths λ =0.8 cm, 3.2 cm, 5.5 cm and 10 cm. Also the polynomial approximation of rigorous results is proposed and the expansion coefficients are found. This allows using of the given data for calculation of scattering characteristics in the case of a polydisperse medium of nonspherical particles.
2 citations
Proceedings Article•
01 Oct 2012TL;DR: In this paper, raindrops are approximated as spheres, and the advantages of the analysis method are used to derive exact calculation of the extinction cross section. And the specific rain attenuation in dB/km as a function of temperature, frequency and rainfall intensity is derived.
Abstract: The attenuation by rain has received much attention [1]–[3] since it is closely related to the quality of communication systems. With the increasing deployment of the higher frequencies in commercial wireless networks, the accurate estimation of the rain attenuation is very important for the reliable design of a radio communication system. Since the attenuation is caused by scattering and absorption of electromagnetic waves by small raindrops, the multiple scattering must be considered, especially at high frequencies. In this paper, raindrops are approximated as spheres, we can use the advantages of the analysis method to derive exact calculation of the extinction cross section. The specific rain attenuation in dB/km as a function of temperature, frequency and rainfall intensity will be derived.
1 citations
TL;DR: An analytical method to evaluate the rain attenuation exceedance probability over a fixed wireless access link is presented and the derived exceedance probabilities are compared with experimental data from ITU-R databank with encouraging results.
Abstract: The ever increasing demand for high date rate multimedia services has led to the deployment of Fixed Wireless Access (FWA) networks operating in frequencies above 10GHz. Propagation characteristics of such networks include line-of-sight (LOS) transmissions highly influenced by the presence of rain. In this paper a methodology for evaluating the outage probability of a FWA channel is introduced, making use of the forward scattering amplitude by distorted raindrops of transmitted signals. Expressions for the imaginary part of the scattering amplitude are derived through a regression fitting analysis on the results of the Method of Auxiliary Sources (MAS) to the problem of electromagnetic scattering from a Pruppacher-Pitter raindrop. These expressions are employed and an analytical method to evaluate the rain attenuation exceedance probability over a fixed wireless access link is presented. The derived exceedance probabilities are compared with experimental data from ITU-R databank with encouraging results.
1 citations
References
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Book•
01 Jan 1978
TL;DR: This IEEE Classic Reissue presents a unified introduction to the fundamental theories and applications of wave propagation and scattering in random media and is expressly designed for engineers and scientists who have an interest in optical, microwave, or acoustic wave propagate and scattering.
Abstract: A volume in the IEEE/OUP Series on Electromagnetic Wave Theory Donald G. Dudley, Series Editor This IEEE Classic Reissue presents a unified introduction to the fundamental theories and applications of wave propagation and scattering in random media. Now for the first time, the two volumes of Wave Propagation and Scattering in Random Media previously published by Academic Press in 1978 are combined into one comprehensive volume. This book presents a clear picture of how waves interact with the atmosphere, terrain, ocean, turbulence, aerosols, rain, snow, biological tissues, composite material, and other media. The theories presented will enable you to solve a variety of problems relating to clutter, interference, imaging, object detection, and communication theory for various media. This book is expressly designed for engineers and scientists who have an interest in optical, microwave, or acoustic wave propagation and scattering. Topics covered include:
5,877 citations
3,500 citations
TL;DR: In this paper, the empirical relation A = aR^{b} between the specific attenuation A and the rain rate R is used in the calculation of rain attenuation statistics.
Abstract: Because of its simplicity, the empirical relation A = aR^{b} between the specific attenuation A and the rainrate R is often used in the calculation of rain attenuation statistics. Values for the frequency-dependent parameters a and b are available, however, for only a limited number of frequencies. Some of these values, furthermore, were obtained experimentally, and may contain errors due to limitations in the experimental techniques employed. The aR^{b} relation is shown to be an approximation to a more general relation, except in the low-frequency and optical limits. Because the approximation is a good one, however, a comprehensive and self-consistent set of values for a and b is presented in both tabular and graphical form for the frequency range f = 1-1000 GHz. These values were computed by applying logarithmic regression to Mie scattering calculations. The dropsize distributions of Laws and Parsons, Marshall and Palmer, and Joss et al., were employed to provide calculations applicable to "widespread" and "convective" rain. Empirical equations for some of the curves of a(f) and b(f) are presented for use in systems studies requiring calculations at many frequencies. Some comparison is also made with experimental results, and suggestions are given regarding application of the various calculations.
674 citations
TL;DR: A critical survey of the literature is presented and an empirical model of the complex refractive indices for ice and liquid water is constructed from this review.
Abstract: A critical survey of the literature is presented. An empirical model of the complex refractive indices for ice and liquid water is constructed from this review. The model is applicable from -20 degrees C to 0 degrees C for ice and from -20 degrees C to 50 degrees C for water. The spectral interval for which the model applies extends from 2 micro, to several thousand kilometers in wavelength for ice and from 2 micro to several hundred meters in wavelength for water.
595 citations
TL;DR: In this paper, a physical model which predicts the shape of water drops falling at terminal velocity in air is presented, based on a balance of the forces which act on a drop falling under gravity in a viscous medium.
Abstract: A physical model which predicts the shape of water drops falling at terminal velocity in air is presented. The model is based on a balance of the forces which act on a drop falling under gravity in a viscous medium. The model was evaluated by numerical techniques and the shape of water drops of radii between 170 and 4000 μ (equivalent to Reynolds numbers between 30 and 4900) was determined. The results of our investigation show that the drop shapes predicted by the model agree well with those experimentally observed in our wind tunnel. Both theory and experiment demonstrate that: 1) drops with radii ≲170 μ are very slightly deformed and can be considered spherical, 2) the shape of drops between about 170 and 500 μ can be closely approximated by an oblate spheroid, 3) drops between about 500 and 2000 μ are deformed into an asymmetric oblate spheroid with an increasingly pronounced flat base, and 4) drops ≳2000 μ develop a concave depression in the base which is more pronounced for larger drop size...
435 citations