Some aspects of tropical rainfall and their effect on microwave propagation

Ajayi, G. O.

doi:10.1002/sat.4600080308

Cited by 20 publications

(16 citation statements)

References 13 publications

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“…Malaysia and South Africa distributions are similar at diameters below 1 mm at these rain rates. The specific attenuation due to rainfall in Butare is computedusing equations (6) and (8). Table 4 shows variation of the attenuation with the transmission frequency.…”

Section: A Variability Of Dsd Modeling In Durban South Africamentioning

confidence: 99%

“…Tropical, subtropical and equatorial regions are characterized by high-intensity rainfall, enhanced frequency of rainfall occurrence and increased presence of large raindrops [6]. Oftentimes rain in the tropics occur in form of cells which are acomplex mixture of stratiform and convective types, with the convective rain contributing over 70 percent of the total rainfall in most cases [7,8].The modeling of DSD in the tropical climate is best suitable with the globally accepted Ajayi and Olsen [6] lognormal model. It has also been established that the three-parameter DSD models are more flexible than two-parameter models in the measurement and estimation of raindrop sizes variability and ensures high representability of the experimented measurement [9].…”

Section: Introductionmentioning

confidence: 99%

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Preliminary Investigation of Raindrop Size Distribution Modelling for Microwave Applications in Rwanda

Adetan¹

2014

IOSRJEN

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Abstract:-The choice of rain drop size distribution(RDSD) model is essential for adequate estimation and prediction of attenuation due to rain in any geographical location or region. Measurements of drop size distributions at Butare (2.6 o S, 29.74 o E); Rwanda is carried out using the Joss-WaldvogelRD-80 disdrometer installed at the National University of Rwanda. Different established distributions are fitted to the measured disdrometer data to model the RDSD for a number of rainfall events. The method of moments (MoM) is adopted for the estimation of theRDSD parameters, while the scattering functions are estimated using the Mie scattering approximation at a temperature of 20 o C for spherical raindrops.A comparative analysis of the proposed model is made with models from other tropical and equatorial regions. Theproposed models are used to estimate the specific rain attenuation over Rwandaand at 2.5 -150 GHz using the estimated R 0.01 value for Rwanda.Between 10 ≤ f ≤ 60 GHz window, the specific rain attenuation increases with corresponding increase in the frequency. The performance above 60 GHz relative to increase in frequency shows no significant change in the specific rain attenuation.The estimated attenuation statistics presented in this study will be useful for the proper design and allocation of adequate fade margins to achieve the expected quality of service (QoS) in a radio communication system operating in this region.

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Section: A Variability Of Dsd Modeling In Durban South Africamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Preliminary Investigation of Raindrop Size Distribution Modelling for Microwave Applications in Rwanda

Adetan¹

2014

IOSRJEN

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“…The rain-attenuation analyses are important for the study of the rain fade characteristics, which is a useful piece of information in the link budget estimation for predicting the expected outage as a result of rain attenuation on a microwave link [4,5]. Long-term rain attenuation data are usually available for the terrestrial links in most tropical regions and so there is the need to convert them for use in satellite applications.…”

Section: Introductionmentioning

confidence: 99%

A New Rain Attenuation Conversion Technique for Tropical Regions

Abdulrahman¹,

Rahman²,

Rahim³

et al. 2010

PIER B

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Abstract-Rain attenuation is one of the most crucial factors to be considered in the link budget estimation for microwave satellite communication systems, operating at frequencies above 10 GHz. This paper presents a mathematical model for converting terrestrial rain attenuation data to be used for satellite applications at Ku-band. In the proposed technique, the ITU-R P 618-9, together with a combination of ITU-R P 530-12 and the revised Moupfouma model have been adopted for satellite and terrestrial rain attenuation predictions, respectively. The model has been used for transforming the measured rain attenuation data of some DIGI MINI-LINKS operating at 15 GHz in Malaysia, to be used for MEASAT 2 applications. It was found that the model predictions are fairly reasonable when compared with direct beacon measurements in Malaysia and similar tropical locations. The model will provide a relatively accurate method for transforming the measured terrestrial rain attenuation to be used for satellite applications; and therefore substantially reduce the cost of implementing Earth-satellite links in some tropical regions that have sufficient rain attenuation data for the terrestrial links.

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“…However, rain-induced attenuation is the major issue at frequencies above 10 GHz, more especially in tropical regions which experience heavier rainfall intensities [1]. Rain attenuation plays significant role in the design of terrestrial and Earth-satellite radio links especially at frequencies above 10 GHz [2].…”

Section: Introductionmentioning

confidence: 99%

“…Even though ITU-R has provided a methodological approach for predicting the rain attenuation on any terrestrial radio link, the model does not perform well in tropical climates because it is based on data collected from temperate regions [2,3]. A number of research works have been published to emphasize the inappropriateness of ITU-R method in tropical regions [2][3][4]. Generally, the required inputs in most attenuation prediction models are the rainfall rate exceeded at %p of time, the effective propagation path length, and the link's operating frequency [5].…”

Section: Introductionmentioning

confidence: 99%

An improved ITU-R rain attenuation prediction model over terrestrial microwave links in tropical region

Islam

Abdulrahman

Rahman

2012

J Wireless Com Network

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An improved approach of predicting rain attenuation cumulative distribution (CD) over terrestrial microwave links operating in tropical regions is presented in this article. The proposed method offers a better extrapolation approach for determining the values of rain attenuation at different exceedance probability from the measured attenuation at 0.01% of the time. The experimental data consist of measured rainfall rates and rain attenuation over six geographically spread DIGI MINI-LINKs operating at 15 GHz in Malaysia. A new set of numerical coefficients was derived for improved rain attenuation CD predictions in the Malaysian tropical climate. In order to test the applicability of the proposed extrapolation method, a validation was performed using rain rate and rain attenuation measurements from five Brazilian and seven Nigerian tropical locations. When tested against measurements, the proposed method seems to provide a significant improvement over the current extrapolation method adopted by ITU-R Recommendations P.530-14, for the prediction of rain attenuation CD over tropical regions.

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Some aspects of tropical rainfall and their effect on microwave propagation

Cited by 20 publications

References 13 publications

Preliminary Investigation of Raindrop Size Distribution Modelling for Microwave Applications in Rwanda

Preliminary Investigation of Raindrop Size Distribution Modelling for Microwave Applications in Rwanda

A New Rain Attenuation Conversion Technique for Tropical Regions

An improved ITU-R rain attenuation prediction model over terrestrial microwave links in tropical region

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