Estimation of Clear-Air Atmospheric Effective Earth Radius (K-Factor) in Calabar

Isaac A Ezenugu

doi:10.11648/j.ijics.20170203.12

Abstract

Microwave radio propagation in terrestrial radio links over the years has earned increased application and there has been renewed attention of studies concerning techniques for estimating the probability of multipath fading distributions. Particularly, the secondary radio parameters remain very important in carrying out these estimations especially the concept of effective earth radius. This study was carried out in Calabar, South-south Nigeria with three years atmospheric parameters data obtained from Nigerian Meteorological Agency (NIMET). International Telecommunication recommendation models were used in obtaining point refractivity gradient with which the effective earth radius factor was determined. The result showed a yearly average value of 1.626091667 for the k-factor and yearly average value of -125.50845 for the point refractivity gradient. There are also monthly and seasonal variations in the two parameters. The highest k-factor of 1.8263 occurred in January whereas the least k-factor of 1.3396 occurred in November.

Highlights

Radio wave communication over the years has been in use in greater capacity as compared to other means of communication [1]
The concept of effective earth as considered in radio and radar communication is seen to be a theoretical value used for the earth radius instead of the actual earth radius; the effective earth radius is used to correct for refraction that is caused by the atmosphere
Point refractive gradient and effective earth radius has been calculate for Calabar using local Nigerian Meteorological Agency (NIMET) radiosonde data for the time span between 2012 and 2014

Summary

Introduction

Radio wave communication over the years has been in use in greater capacity as compared to other means of communication [1] This can be seen in both civil and military operations the world over and are applied in transmitting voice, data and video to various location [2, 3, 4]. Some parameters such as effective earth radio factor, k and the point refractivity gradient, dN1 must be set carefully to optimize the system performance. For such locations where atmospheric data were not available, k-factor value of 4/3 is taken as a standard value and estimated values of dN1 are provided by ITU tables for point refractivity for such conditions [13]. The main focus is to identify the temporal distribution of the k-factor in Calabar

Effective Earth Radius

Determination of K – Factor

Results and Discussion

Conclusion