Shibuya Method and Modified ITU Knife Edge Diffraction Loss Model for Computing N Knife Edge Diffraction Loss

Kalu Okore Ama

doi:10.11648/j.ajsea.20170602.13

Abstract

In this paper, algorithm for applying Shibuya multiple knife edge diffraction method and modified ITU-R P 526-13 knife edge diffraction loss approximation model are presented. Particularly, in this paper, algorithm for using the two models for computing N knife edge diffraction loss is presented. Requisite mathematical expressions for the computations are first presented before the algorithm is presented. Then sample 10 knife edge obstructions are used to demonstrate the application of the algorithm for C-band 6 GHz microwave link. The results showed that for the 10 knife edge obstructions spread over a path the maximum virtual hop single knife edge diffraction loss is 14.97452dB and it occurred in virtual hop j =6 which has the highest diffraction parameter of 1.027072 and the highest line of site (LOS) clearance height of 8.480769m. The minimum virtual hop single knife edge diffraction loss is 7.881902 dB and it occurred in virtual hop j =9 which has the lowest diffraction parameter of 0.114761 as well as the lowest LOS clearance height of 0.628571m. The algorithm is useful for development of automated multiple knife edge diffraction loss system based on Shibuya method and the modified ITU-R P 526-13 knife edge diffraction loss approximation model.

Highlights

Diffraction loss is one of the key components of pathloss that is udsed in link budget for line of sight (LOS) microwave link [1,2,3,4,5]
In order to simplify the analysis of diffraction loss, an isolated obstruction like hill or building can be considered as a knife edge obstruction [14,15,16]
This paper focuses on presenting a method computing multiple knife edge diffraction loss where

Summary

Introduction

Diffraction loss is one of the key components of pathloss that is udsed in link budget for line of sight (LOS) microwave link [1,2,3,4,5]. Diffraction occurs when wireless signal encouter obstacle in its path [7,8,9,10,11] In such case, the signal bend and move round the obstacle to the receiver. Available studies show that computation of multiple knife edge diffraction is quite complex [18,19,20]. Most studies limit the multiple knife edge computation to three obstructions. Algorithm is presented which can be used to compute diffraction loss for any number of knife edge obstructions. The algorithm is based on the use of Shibuya multiple knife edge diffraction method and the modified ITU-R P 526-13 knife edge diffraction loss approximation model are presented. Sample 10 knife edge obstructions are used to demonstrate the applicability of the algorithm

Methodology

Numerical Example and Discussion of Results

Conclusion