Comparative Study of Radius of Curvature of Rounded Edge Hill Obstruction Based on Occultation Distance and ITU-R 526-13 Methods

摘要

In this paper, comparative study of the ITU 526-13 method and the occultation distance-based method for computing the radius of curvature for rounded edged fitted to the vertex of hilltop obstruction is presented. In the study, path profiles of microwave links with isolated single edged hilltop and another path profile with isolated double edged hilltop are used. The frequencies considered are from the 1.5GHz in the L-band to 36GHz in the K-band. The result show that for all the frequencies considered, the occultation distance for the single edged hilltop remained constant at 80.923 m and that for the double edged hilltop remained constant at 532.203 m. Also, while the radius of curvature by the ITU 526-13 method varies with frequency in the two path profiles considered, the radius of curvature by the occultation distance method remained constant for all the frequencies considered in each of the two path profiles considered. Also, for the double edged hilltop, the radius of curvature from ITU 526-13 method greatly exceeded the radius of curvature by the occultation distance method for all the frequencies considered. The least difference in about 58% at frequency of 1.5GHz and the difference increased to about 115% at 36GHz. However, for the single edged hilltop, the radius of curvature for the two methods are relatively equal for frequencies above 6GHz. Essentially, ITU 526-13 method works well like the occultation distance-based method for the single edged hilltop. Further studies are therefore required to determine the situations under which the ITU 526-13 method can be applied in computing the radius of curvature for rounded edge approximation used in diffraction loss computation.