INVESTIGATION OF THE EFFECTS OF SECONDARY RADIOCLIMATIC VARIABLES ON RADIO SIGNAL AT THE TROPOSPHERE

In order to propose a reasonable prediction for radioclimatic study, a reliable radio propagation data is required. This radio propagation data can be either primary or secondary. The secondary data can be estimated from a relevant primary data which include temperature, pressure and humidity or water vapour pressure, while secondary radioclimatic data includes refractivity (N), refractive index (n) and effective earth's radius (k-factor). The main concern of this work is secondary data, of which the measurement were made at Nsukka 6o 45N latitude and 7o 30E longitude, South -Eastern Nigeria, using an automatic wireless weather station Vantage Pro2, positioned at the surface level installed at National Center for Basic Space Science (NCBSS) Nsukka. The measurements of the primary variables were made at time interval of 30 minutes daily from August 2013 to July 2014. The results obtained show seasonal variation of the temperature and relative humidity. This leads to the increase in the values of radio refractivity and refractive index. The result also, show that the k-factor values for those months were at the range of 1.555 - 1.653, which is above the global standard value 1.333. The effect of this result leads to major propagation condition known as super- refraction which affects radio waves and lead to signal interference over Nsukka.

Title Page    
Approval                          
Certification                                                                                                                                                                                                                                                                                                                     
Dedication                                                                                                                                                                                                           
Acknowledgement    
Abstract                                                                                                                                                                                                                                        
Table of Contents                                                                                                                                                                                                                     
List of  figure
List of Tables                                                                                                                                                                                                                                    
CHAPTHER ONE: INTRODUCTION                                                           
1.1     Preamble                                    1
1.2     Layers of the Atmosphere                        3
1.2.1    The Troposphere                                3
1.2.2    Stratosphere                                    4
1.2.3    The Ionosphere                                4
1.2.3.1  D Region                                    5
1.2.3.2   E Region                                    6
1.2.3.3  F Region                                    7
1.3    Problem Statement                8                                                                                                   
1.4    Objectives                                    8                                                                                    
1.5    Scope of the Work                                8     
                                                                                   
CHAPTHER TWO: LITERATURE REVIEW   
2.1    Preamble                                    9
2.2     Basic Theory                                11
2.2.1    Ground Wave or Surface Wave                        12
2.2.2    Space Wave Propagation                            13
2.2.3    Sky Wave Propagation                            13
2.2.4    Tropospheric scatter Wave                        14
2.3     Refraction of Waves                            15          
2.4     Diffraction (Fresnel Zone)                        16                                                        
2.4.1    Diffraction Fading Application                        17
2.4.2    Fade Depth Application                             18
2.5     Electromagnetic wave Propagation                    19   
2.6     Signal Loss                                    21

CHAPTHER THREE: MATERIALS AND METHODS
3.1        Method of Measurement  28
3.2      Calculation of the Radio Refractivity                    29 
3.3        Estimation of Refractive Index (n)                    31
3.4        Calculation of Effective Earth’s Radius (k-factor)  33

CHAPTHER FOUR:
 RESULTS                                          37
 
CHAPTHER FIVE:
 DISCUSSION                         45
 
CHAPTHER SIX:
 SUMMARY, CONCLUSION AND RECOMMENDATION
6.1     Summary                                     49  
6.2     Conclusions                                49
6.3     Recommendations                                50
References                                    51
Appendices