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Determination of Millimetric Signal Attenuation Due to Rain Using Rain Rate and Raindrop Size Distribution Models for Southern Africa

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Determination of Millimetric Signal Attenuation Due to Rain Using Rain Rate and Raindrop Size Distribution Models for Southern Africa DETERMINATION OF MILLIMETRIC SIGNAL ATTENUATION DUE TO RAIN USING RAIN RATE AND RAINDROP SIZE DISTRIBUTION MODELS FOR SOUTHERN AFRICA by Senzo Jerome Malinga A THESIS submitted in fulfillment of the requirements for the degree PhD (ELECTRONIC ENGINEERING) School of Engineering College of Agriculture, Engineering, and Science UNIVERSITY OF KWAZULU-NATAL Durban, South Africa March 2014 Supervisor: Professor Thomas Joachim Odhiambo Afullo Approved by: Supervisor: Professor Thomas Joachim Odhiambo Afullo As the candidate’s Supervisor I agree to the submission of this thesis. Signed………………………………………Date……………………………………….. ii COLLEGE OF AGRICULTURE, ENGINEERING AND SCIENCE Declaration 1 - Plagiarism I Senzo Jerome Malinga declare that 1. The research reported in this thesis, except where otherwise indicated, is my original research. 2. This thesis has not been submitted for any degree or examination at any other university. 3. This thesis does not contain other persons’ data, pictures, graphs or other information, unless specifically acknowledged as being sourced from other persons. 4. This thesis does not contain other persons' writing, unless specifically acknowledged as being sourced from other researchers. Where other written sources have been quoted, then: a. Their words have been re-written but the general information attributed to them has been referenced b. Where their exact words have been used, then their writing has been placed in italics and inside quotation marks, and referenced. 5. This thesis does not contain text, graphics or tables copied and pasted from the Internet, unless specifically acknowledged, and the source being detailed in the thesis and in the References sections. Signed…………………………………………………..Date……………………………………………… iii COLLEGE OF AGRICULTURE, ENGINEERING AND SCIENCE Declarations 2 - Publications DETAILS OF CONTRIBUTION TO PUBLICATIONS that form part and/or include research presented in this thesis (include publications in preparation, submitted, in press and published and give details of the contributions of each author to the experimental work and writing of each publication). Journal Publications 1. Senzo J. Malinga and Pius A. Owolawi, “Obtaining Raindrop Size Model Using the Method of Moments and Its Applications for South African Radio Systems,” PIER B Journal, Vol. 46, pp. 119-138, 2013. In this paper, the Raindrop Size Distribution (DSD) modeling and analysis are presented. Drop sizes are classified into different rain types, namely: drizzle, widespread, shower and thunderstorm. The gamma and Lognormal distribution models are employed using the method of moments estimator, considering the third, fourth and sixth order moments. The results are compared with the existing raindrop size distribution models such as the three parameter lognormal distribution proposed by Ajayi and his colleagues and Singapore’s modified gamma and Lognormal models. This is then followed by the implementation of the proposed raindrop size distribution models on the computation of the specific rain attenuation. Finally, the paper suggests a suitable DSD model for the region with its expressions. The proposed models are very useful for the determination of rain attenuation for terrestrial and satellite systems. 2. Senzo J. Malinga, P.A. Owolawi and T.J.O. Afullo, “Determination of Specific Rain Attenuation using Different Total Cross Section Models for Southern Africa,” – Africa Research Journal Vol. 104, No. 3, 2013 (accepted). Electromagnetic waves whose frequency is beyond 10 GHz are severely attenuated by rain. This is true in both satellite and terrestrial links. The rain attenuation is mainly manifested in the form of scattering and absorption. In the paper presented here, various total cross section models are used to calculate the iv specific attenuation due to rain for the frequencies between 1 to 100 GHz. The DSD modelling is done using the Method of Moments, from which the specific attenuation due to rain is computed. Comparisons are then drawn between the models proposed, well known models in existence, and theoretical results for three different polarizations at 19.5 GHz frequency. Conference Publications 1. P.A. Owolawi, S.J. Malinga and T.J.O. Afullo, “Estimation of Terrestrial Rain Attenuation at Microwave and Millimeter Wave Signals in South Africa Using the ITU-R Model,” PIERS Proceedings, Kuala Lumpur, Malaysia, March 27-30, 2012, pp. 952-962. In this paper, experimental rain rate measurements are presented together with rain attenuation results computed via the application of the International Telecommunication Union’s Recommendations (ITU-R) model for attenuation due to rain in terrestrial links in South Africa. A total of nineteen case study locations, at least every province in South Africa represented by one, are used for this presentation. The paper specifically presents results of the total path and specific attenuation for terrestrial links for three different types of polarizations in the frequencies ranging from 1 to 400 GHz. The implications of rain attenuation to the system designers are evaluated by finding link distance chart, and design link-budget at the chosen frequency range. The results of this work can be used in planning links for both microwave and millimeter broadband wireless networks in South Africa such as Local-Multipoint-Distributed- Services (LMDs). 2. Mulangu, C.T.; Malinga, S.J.; Afullo, T.J.O., "Impact of rain on microwave radars," 2012 International Conference on Electromagnetics in Advanced Applications (ICEAA), vol., no., pp.1088,1091, 2-7 Sept. 2012, Cape Town The most important source of disturbance in microwave links is caused by precipitation attenuation due to mainly snow and rain via scattering and absorption. In this paper, two year experimental rain rate data is used to perform the reflectivity profile of radar at various rain rates using the lognormal DSD model for Durban. 3. S.J. Malinga, P.A. Owolawi, and T.J.O. Afullo, “Estimation of Rain Attenuation at C, Ka, Ku, and V Bands for Satellite Links in South Africa,” PIERS Proceedings, Taipei, Taiwan, March 25-28, 2013, pp. 948-958. v The fast growth in telecommunications, increased demand for bandwidth, congestion in lower frequency bands and miniaturization of communication equipment have forced the designers to employ higher frequency bands such as the C (4 to 8 GHz), Ka (26.5 to 40GHz), Ku (12-18 GHz) and V (40-75 GHz) bands. Rain is the most deleterious to signal propagation in these bands. The contribution of rain attenuation to the quality of signal in these bands, especially in the tropical and subtropical bands in which South Africa is located, need to be studied. The aims of this paper are to estimate the magnitude of rain attenuation using the ITU-R model, carry out link performance analysis, and then propose reasonable, adequate fade margins that need to be applied for all provinces in South Africa. 4. S.J. Malinga, P.A. Owolawi, and T.J.O. Afullo, “Computation of Rain Attenuation through Scattering at Microwave and Millimeter Bands in South Africa,” PIERS Proceedings, Taipei, Taiwan, March 25-28, 2013, pp. 959-971. In this presentation, both measured and calculated rain attenuation are obtained using two methods. These methods are the Pruppacher-Pitter technique (non-spherical method) and the Mie Scattering technique (spherical method). Incorporation of available DSD data and measured rain rate with the derived scattering amplitude coefficients is then done to estimate the total and specific attenuation due to rain for the South Africa region. Comparison between the results obtained with the few known rain attenuation models and one-year attenuation measurement data in South Africa (Durban) are then drawn. Further, the results obtained are tested for both satellite and terrestrial radio links at particular rain rates and specific frequencies. 5. P.A. Owolawi, S.J. Malinga, T.J.O. Afullo “Computation of rain scattering properties at SHF and EHF for radio wave propagation in South Africa”, URSI Commission F Triennial, April 30 – May 3, 2013, Ottawa, Canada. In this paper computation of scattering parameters at 1 – 100 GHz frequencies under the influence of a rainy medium are presented. The characteristics of scattering parameters at these frequencies are integrated and computed with lognormal raindrop size distribution for four rain types, and the results are used to compute the specific attenuation due to rain as well as the associated specific phase shift. The calculated specific attenuation due to rain and its phase shift results are compared with tropical and temperate regions’ counterparts. In addition, analytical coefficients of the fundamental specific rain attenuation and specific phase shift are derived in the same frequency range of different rain types in Southern Africa. vi 6. Chrispin T. Mulangu, Senzo J. Malinga, Thomas J. Afullo, “Prediction of Radar Reflectivity along Radio Links”, PIERS Proceedings, pp. 264 – 267, Taipei, March 25 – 28, 2013 Radiowaves propagating through a rain zone will be scattered, depolarized, absorbed and delayed in time. All these effects of rain on the wave propagation are related to the frequency at which the signal is transmitted and polarization of the wave as well as to the rain rate, which influences the form and size distribution of the raindrop. The average power received by the bistatic radar is proportional to the product of reflectivity and attenuation. These can be measured in practice but sometimes there is a need to determine them separately. In
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