| Popis: |
In this paper, remodeling of Lee’s piecewise knife diffraction loss model is presented. The original Lee’s piecewise knife diffraction loss model is expressed as a function of Fresnel-Kirchoff diffraction parameter. The computation of the Fresnel-Kirchoff diffraction parameter requires detailed terrain and link parameters. However, for quick link planning the Fresnel-Kirchoff diffraction parameter can be computed from the knowledge of the line of site percentage clearance alone. Moreover, in line of site link design, the required or acceptable obstruction clearance is specified in terms of line of site percentage clearance. Consequently, in this paper, the Lee’s model is remodeled into new piecewise functions that are entirely functions of line of site percentage clearance. The new version of Lee’s model is validated with the results of knife edge diffraction loss obtained from the original Lee’s piecewise knife diffraction loss model. With the new model it is easier to determine the diffraction loss that will be caused by any obstruction at a given line of site percentage clearance. |
