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Computation of the Scattering Parameters Using Indian Lognormal Drop Size Distribution at 16, 19.3 and 34.8 GHz for Spherical and Oblate Spheroidal Rain Models

Author(s): Aderemi Sikiru Adekola

Journal: Asian Journal of Scientific Research
ISSN 1992-1454

Volume: 1;
Issue: 3;
Start page: 213;
Date: 2008;
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Keywords: Oblate spheroidal raindrops | spherical rain model | specific attenuation | specific phase shift | drop size distribution | rain rate | scattering

Calculations of Millimeter-wave rain scattering parameters are made at 16, 19.3 and 34.8 using spherical and oblate spheroidal rain models. Computations are made at angle of incidence of 0 and 90 ° for the oblate spheroidal rain model. The characteristic of the difference between the two models with rain rate are studied at incidence angle of 0 ° to allow us determine their suitability in a tropical environment. Some propagation parameters are evaluated using the Indian lognormal and Marshall and Palmer (MP) Drop Size Distributions (DSD`s). Marshall and Palmer DSD model could underestimate rain-induced attenuation at all the frequencies in the rain rate range of 0.25≤R100 mm h-1 if adopted for radio wave propagation prediction on tropical path. However, Indian data compare well with MP at rain rate in the range 50≤R≤100 mm h-1. Similarly, spherical rain model could underestimate the specific attenuation with a maximum margin of 3.4 dB km-1 at 34.8 GHz and specific phase shift of 15.7 ° km-1 at 16 GHz, both at rain rate of 150 mm h-1. The empirical scaling relationship between the radar reflectivity η and rain rate R (η = aRb) are derived for the Indian DSD and the coefficients a and b compare well with those of Aydin and Lure.

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