A review of theories of coherent radio wave propagation through precipitation media of randomly oriented scatterers, and the role of multiple scattering

Olsen, Rasmus Løvenstein

doi:10.1029/rs017i005p00913

Cited by 25 publications

(8 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A well known approach is the one described by the integral equation of Twerskii-Foldy for the coherent field [31]. Supposing a low particle density and a negligible particle size so that the location and the characteristics of each scatterers are independent of the location and characteristics of other scatterers (thus simplifying the statistical averaging), it can be shown that behaves locally as a plane wave and satisfies the Helmholtz homogeneous equation , where the effective (complex) propagation constant is given by [23], [30] (1)…”

Section: A Theoretical Considerationsmentioning

confidence: 99%

See 1 more Smart Citation

Numerical investigation of intense rainfall effects on coherent and incoherent slant-path propagation at K-band and above

Marzano

Roberti

2003

IEEE Trans. Antennas Propagat.

View full text Add to dashboard Cite

A model investigation is carried out to analyze the impact of intense rainfall on slant-path microwave propagation, using a rainfall microphysical model. The effects are evaluated both for path attenuation, undergone by coherent radiation, and for multiple scattering phenomena, originating incoherent radiation along the path. Atmospheric spatial inhomogeneity is taken into account by considering a precipitating-cloud three-dimensional distribution, obtained from the numerical outputs of a microphysical cloud-resolving model. The electromagnetic propagation model is formulated by means of the radiative transfer theory, rigorously defining the forward coherent multiple scattering effect within this framework. The propagation model is applied both to simplified rain slabs and to vertically and horizontally inhomogeneous raining cloud structures in order to compare the impact of atmospheric models on coherent and incoherent propagation. Beacon frequencies between 20-50 GHz are considered together with elevation angles between 20 -40 and surface rain rates from 1 to 100 mm/h. Appropriate sensitivity analysis parameters are defined to present and discuss the numerical results. The main conclusion of this numerical study is that the impact of the convective rainfall structure can be significant both in determining total attenuation and to quantify multiple scattering contribution to the received power. For intense rainfall, the use of a rain slab model can overestimate coherent attenuation and, at the same time, underestimate incoherent intensity. The analysis of realistic raining clouds structures reveals the significance of modeling the volumetric albedo of precipitating ice, particularly at V-band. Total path attenuation can strongly depend on the pointing direction of the receiving antenna due to the intrinsic variability of the precipitating cloud composition along the slant path. Coupling cloud-resolving models with radiative transfer schemes may be foreseen as a new approach to develop statistical prediction methods at Ka-band and above in a way analogous to that pursued by using weather-radar volume data.Index Terms-Cloud and rainfall modeling, earth-satellite millimeter-wave links, microwave propagation, multiple scattering effects, radiative transfer theory, rain attenuation.

show abstract

Section: A Theoretical Considerationsmentioning

confidence: 99%

“…Excellent review works describe these efforts [17], [23], [24], [27]. A well known approach is the one described by the integral equation of Twerskii-Foldy for the coherent field [31].…”

Section: A Theoretical Considerationsmentioning

confidence: 99%

Numerical investigation of intense rainfall effects on coherent and incoherent slant-path propagation at K-band and above

Marzano

Roberti

2003

IEEE Trans. Antennas Propagat.

View full text Add to dashboard Cite

show abstract

“…Once these parameters have been determined for a rain scatter volume, the transmission matrix T of the rain volume can be calculated for other frequencies and directions of incidence of a plane wave. The transmission matrix of rain volumes has been calculated using the coherent forward multiple scattering approximation described in [6].…”

Section: Polarimetric Radar Measurements In Rainmentioning

confidence: 99%

Polarimetric Radar Measurements of Rain and Radar Derived Attenuation and Depolarization in Rain at 20/30 GHz

Schnabl¹

1988

18th European Microwave Conference, 1988

View full text Add to dashboard Cite

Propagation properties of rain are derived from radar measurements. The radar measurements of rain have been performed using the polarimetric DFVLR weather radar. Measurements of the horizontal reflectivity, differential reflectivity and linear depolarization ratio in rain are presented. The mean canting angle of raindrops is directly derived from measurements at several linear polarizations. The radar data is corrected for propagation effects which occur on the way between radar and scatter volume. Attenuation and depolarization are derived from the corrected radar data for the frequenlcies of planned satellite-earth links at 20 and 30 Gllz. INTRODUCTION Satellite-earth communication links at 20/30 GHz can be severely influenced by different sorts of precipitation in the atmosphere (rain, snow, etc.) with regard to attenuation, depolarization and phase shift. The polarimetric C-band DFVLR weather radar enables a study of the influence of different hydrometeors by scanning the propagation path. In this paper the attenuation and depolarization of plane waves propagating through rain are determrined by means of radar measurements. CALCULATIQN OF RADAR BACKSCATTERIN(GBY RAINThe radar backscattering of rain volumes was calculated in order to derive model parameters from radar measurements. Meteorological scatter volumes consist of many single scatterers (raindrops) which are moving relative to each other. The scatter volume is an incoherent scatterer; the backscattered wave is only partially coherent and in general partially polarized. Partially coherent waves can be represented by their Stokes-vectors g [1]. The backscattering process can then be described by the MUller-matrix M of the scatter volume [3] and the received power P is given by:where j is the Stokes-vector of the transmit polarization, M is the MUller-matrix of the rain volume and g, is the Stokes-vector of the receive polarization.The first order multiple scattering approximation (single scattering + propagation effects) can be applied to rain volumes. In that case the elements of the MiUller-matrix of a volume containing independent single scatterers consist of ensemble averages given by: (Ornmpq> = |JJJ N(D) p99(9 ,p) Smn(D, 9, 6p)S;D, , 6p)d9pdSdD x x Je -Akm ± k)r e(kpkq)r d(V 2 v where D is the equivalent raindrop diameter, N(D) is the drop size distribution, 19,p are drop orientation angles and p, (,9, p) is their distribution. Sk, is the backscattering amplitude of a single raindrop for transmit polarization I and receive polarization k. * denotes complex conj'ugation. k, is the effective propagation constant in the rain volume for a wave of polarization i. V is the pulse volume and r is the radial distance of a raindrop from the beginning of the rain volume. The first term on the right side of eq.(2) (integrals

show abstract

“…3) The above propagation constants can be expressed as (1) (2) where is the free-space propagation constant, and expressions for and as functions of the microphysical characteristics of the rain medium have been provided by different authors [2], [13]. With these premises, fields at points B and C, separated by distance , can be related as follows:…”

Section: Propagation Effects On Scattering and Covariance Matrix mentioning

confidence: 99%

“…Modeling and analysis of rain effects on coherent wave propagation have been addressed by different authors. Of particular interest is the review and comparison of the different coherent models developed by Olsen [2], where attention is focused on the similarities and differences between several general formulations for precipitation media with random scatterer orientations, and the implications of realizing different assumptions and considerations about the microphysical properties of the medium (distribution of sizes, orientations, etc.) on the expressions for the propagation constants.…”

Section: Introductionmentioning

confidence: 99%

Maximum-likelihood estimation of specific differential phase and attenuation in rain

Rio

Antar

Fábregas³

2003

IEEE Trans. Geosci. Remote Sensing

View full text Add to dashboard Cite

Abstract-Precise estimation of propagation parameters in precipitation media is of interest to improve the performance of communications systems and in remote sensing applications. In this paper, we present maximum-likelihood estimators of specific attenuation and specific differential phase in rain. The model used for obtaining the cited estimators assumes coherent propagation, reflection symmetry of the medium, and Gaussian statistics of the scattering matrix measurements. No assumptions about the microphysical properties of the medium are needed. The performance of the estimators is evaluated through simulated data. Results show negligible estimators bias and variances close to Cramer-Rao bounds.

show abstract

A review of theories of coherent radio wave propagation through precipitation media of randomly oriented scatterers, and the role of multiple scattering

Cited by 25 publications

References 37 publications

Numerical investigation of intense rainfall effects on coherent and incoherent slant-path propagation at K-band and above

Numerical investigation of intense rainfall effects on coherent and incoherent slant-path propagation at K-band and above

Polarimetric Radar Measurements of Rain and Radar Derived Attenuation and Depolarization in Rain at 20/30 GHz

Maximum-likelihood estimation of specific differential phase and attenuation in rain

Contact Info

Product

Resources

About