Empirical Validation Of Effective Earth Radius Adjustment Factors For Earth Bulge and Diffraction Loss Parameters Computation

Eduediuyai Dan,Constance Kalu ,Ogungbemi Emmanuel Oluropo

doi:10.11648/j.ijssam.20170202.11

Abstract

In this paper, the effect of effective earth radius adjustment factors (k-adjustment factors) on various parameters associated with single knife edge diffraction loss is studied. The parameters considered are, the earth bulge, Fresnel-Kirchoff diffraction parameter and the number of Fresnel zones that are partially or fully blocked by obstruction in the signal path. The k-adjustment factors analytical expressions are derived and then validated using empirical elevation profile data for line-of-sight (LOS) communication link between Eket and Akwa Ibom state University. Also, k-factors considered in this paper are k1 = 0.5, k2 = 0.9 and k3= 1.333. In all, the results show that when the value of any of the three parameters is known at a given k-factor, k1, then the value of that parameter can be determined at any other k-factor, k2 by adding the k1-to-tk2 adjustment factor of that parameter to the value of the parameter at k1. The result is essential is evaluating the influence of variations in effective earth radius factor on the parameters associated with single knife edge diffraction loss.

Highlights

In the communication industry, Fresnel geometry is usually used in the analysis of line-of-sight (LOS) communication link design
The Fresnel geometry is used in the analysis of the knife edge diffraction loss for such LOS link in situations where obstructions intrude into the key Fresnel zones of the signal path
Elevation data for a LOS link between Eket and Akwa Ibom state University are used along with mathematical expressions stated in this paper to determine the various parameters associated with single knife edge diffraction loss

Summary

Introduction

Fresnel geometry is usually used in the analysis of line-of-sight (LOS) communication link design. In order to ensure clear line of sight the curvature of the earth and atmospheric refraction effect must be considered. In LOS communication link design, the effective earth radius K-factor takes into account the curvature of the earth and atmospheric refractivity which bends the beam either up or down [13,14,15]. Effective earth radius is the radius of a hypothetical spherical Earth, without atmosphere, for which propagation paths follow straight lines, the heights and ground distances being the same as for the actual Earth in an atmosphere with a constant vertical gradient of refractivity [15]. For LOS link design, the effective earth radius factor (k- factor) must be set carefully to optimize its performance

Methods

Results

Conclusion