Abstract
In this paper, algorithm for computing N knife edge diffraction loss using Epstein-Peterson method and International Telecommunication Union (ITU) knife edge diffraction loss approximation model 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 L-band 1 GHz microwave signal. The results showed that for the 10 knife edge obstructions spread over a path length of 36 km the maximum virtual hop single knife edge diffraction loss is 8.054711 dB and it occurred in virtual hop j =10 which has the highest diffraction parameter of 0.233333. However, the virtual hop j =10 has line of site (LOS) clearance height of 2.333333 m whereas the highest LOS clearance is 3.454545 m and it occurred in virtual hop j =6. The minimum virtual hop single knife edge diffraction loss is 6.109884 dB and it occurred in virtual hop j =3 which has the lowest diffraction parameter of 0.008909 as well as the lowest LOS clearance height of 0.142857 m. The algorithm is useful for development of automated multiple knife edge diffraction loss system based on Epstein-Peterson method and ITU knife edge diffraction loss approximation model.
Highlights
Propagation paths of line of sight microwave signals are in many cases obstructed by obstacles [1, 2]
The multiple knife edge computation is based on the Epstein-Peterson method [9,10,11,12,13] whereas the International Telecommunication Union Recommendations (ITU-R) P 526-13 knife edge diffraction loss approximation model [14,15,16,17] is used to determine the diffraction loss for any diffraction parameter obtained for each of the knife edge obstruction
The Procedure for computing N knife edge diffraction loss using Epstein-Peterson method and the ITU knife edge diffraction loss approximation model is as follows: Step 1: For j = 0 to N +1 obtain height H (j) of obstruction, where j includes the transmitter with j=0, the receiver with j =N +1and the N obstructions with j =1 to N
Summary
Propagation paths of line of sight microwave signals are in many cases obstructed by obstacles [1, 2]. There are always two or more obtrusions that are often located in the signal path In such case, multiple knife edge diffraction methods are used to determine the expected diffraction loss [5, 6]. Studies have shown that computation of multiple knife edge diffraction loss is complex and it complexity increases especially as the number of knife edge obstructions considered increases [7, 8]. An algorithm that can be used to determine the diffraction loss of any number of knife edge obstruction is presented. Sample 10 knife edge obstructions are used to demonstrate the applicability of the algorithm
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