کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
8208307 | 1531901 | 2018 | 6 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Anomalous waves propagating at very high frequency in the atmosphere and their disturbances due to changes in refractivity profiles
ترجمه فارسی عنوان
امواج غیرمعمول در فرکانس بسیار زیاد در فضا و اختلالات آنها به علت تغییرات پروفیلهای رفراکشن
دانلود مقاله + سفارش ترجمه
دانلود مقاله ISI انگلیسی
رایگان برای ایرانیان
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
فیزیک و نجوم
فیزیک و نجوم (عمومی)
چکیده انگلیسی
Anomalous waves propagation is severely affected due to almost always present variations in refractivity under various environmental conditions at different time, location and frequency. These conditions, representing different state of the atmosphere including e.g. foggy, rainy and cloudy etc., not only degrade the quality of the signal but sometimes completely eradicate the communication link. Such severe impact on propagation cannot be ignored by the designers of communication systems. The aim of this research is to present correlation between experimental and modelled link losses for variations in refractivity values recommended by International Telecommunication Union-Recommendations (ITU-R) as well as that of standard profiles. To do so, a communication setup of 50â¯km over the Sea operating experimentally over a period of a year at 240â¯MHz is analyzed for different refractivity profiles and their impact on propagation. A median value is taken for every set of 6000 values taken from the recorded data set of more than 48 million experimental link losses. This reduces the huge data set of the experimental link losses to 8000 values only. This reduced data set of experimental and modelled link losses were correlated and investigated for different evaporation duct heights throughout the year. For the considered link, the ITU-R refractivity profile was found to perform better than the standard refractivity profile. However, the new findings as observed in this research, which may be helpful for the recommendations authorities, is the existing of evaporation duct up to 10â¯m height.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Results in Physics - Volume 8, March 2018, Pages 496-501
Journal: Results in Physics - Volume 8, March 2018, Pages 496-501
نویسندگان
Imtiaz Alam, Asad Waqar, Muhammad Aamir, Shahzad Hassan, Syed Asim Ali Shah,