Research Article Analysis of Worst-month Relationship with Annual Rain Attenuation in Malaysia

Abstract: The main of this study is to study effect of rain attenuation during the annual and worst month towards communication link especially in the region where heavy rain is a main factor to signal degeration at high frequencies above 10 GHz. Spectral congestion due to the high demand in satellite communication has enforced the development of the conventional frequency bands. Lower frequency band have shifted to higher frequency band such as microwave frequency in order to provide higher data rates as well as wider bandwidths. However, rain fade has become the major hindrance which could cause severe perturbation towards wireless communication tools and satellite communications. Therefore, in this study, analysis of 1 year rain attenuation measurement was done, in order to observe the relationship between the average worst month statistics with the average annual distribution. The result obtained was found to be large different with the one proposed by ITU, hence for better accuracy, the values of Q 1 and β was modified to be adapted in Malaysia

Analisis kesan frekuensi dan sudut dongakan terhadap pelemahan hujan di Malaysia

Kesesakan spektrum jalur frekuensi yang telah ditetapkan sejak sekian lama telah mendorong kepada penggunaan frekuensi yang lebih tinggi iaitu melebihi 10 GHz bagi memenuhi kehendak dan keperluan para pengguna. Namun demikian, operasi di jalur frekuensi ini akan menyebabkan sistem lebih mudah terdedah kepada kehilangan isyarat akibat dari fenomena alam semulajadi seperti hujan lebat. Disebabkan oleh kesan pudaran hujan, ramalan pelemah hujan menggunakan taburan kadar hujan 1-minit menjadi semakin penting. Ramai penyelidik telah mencadangkan pelbagai jenis model ramalan untuk menganggar pelemahan hujan di seluruh dunia. Namun demikian, tidak ada model yang sesuai yang boleh meramalkan pelemah hujan dengan tepat. Di Universiti Sains Malaysia (USM), model International Telecommunication Union–Region (ITU-R) telah menunjukkan ramalan yang terbaik berbanding model-model yang lain. Model ITU-R digunakan untuk menganalisis kesan-kesan pelemahan hujan pada frekuensi dan sudut dongakan yang berbeza. Daripada analisis yang telah dilakukan, didapati bahawa peningkatan frekuensi operasi dan penurunan dalam sudut dongakan akan mengakibatkan peningkatan dalam pelemahan hujan. Namun demikian penjelasan seperti di atas boleh dilihat bagi sudut dongakan melebihi ketinggian 50°