ESTIMATION OF RADIO FIELD STRENGTH AND HORIZON DISTANCE OVER NIGERIA

Abstract

This research studied the surface radio refractivity, NS over seven locations [Akure (7.25oN, 5.21oE), Lagos (6.30oN, 3.20oE), Abuja (7.10oN, 9.25oE), Jos (9.88oN, 8.86oE), Makurdi (7.30oN, 8.53oE), Port-Harcourt (4.20oN,7.00oE), and Nsukka (6.90oN,7.67oE)] in Nigeria, using two years (Jan. 2011-Dec. 2012) archived data of temperature, pressure and relative humidity as provided by Tropospheric Data Acquisition Network (TRODAN) of the Centre for Atmospheric Research Anyigba, Kogi State. The data were used to calculate the surface radio refractivity and its diurnal, daily and seasonal variations were analysed. The results obtained were then used to calculate the Radio Horizon Distance (RDH) and studied the Field Strength Variability (FSV). Results showed that NS was high in the morning and evening hours while the values were very low between 12:00 to 16:00 hr. Local Time (LT) over Nigeria. Moreover, NS values were low during the dry season months and high during the wet season months and also there was high value of NS at the coast compared with the inland areas. The average values of NS for Abuja, Akure, Jos, Lagos, Markurdi, Nsukka and Port-Harcourt are 355, 362, 303, 391, 375, 361 and 399 Nunits respectively. Furthermore, the average values of FSV over all the stations are 30.38, 20.16, 21.39, 24.21, 24.31, 21.49, and 21.48 dB and that the FSV values were high during the dry season months and low during the wet season months. It was also revealed that the RDH values were generally low during the wet season months and high during the dry season months. It implies that there will be high loss of radio signals in the coastal areas and the radio waves propagating through the atmosphere may suffer total absorption. The average output of a receiving antenna in Abuja, Akure, Jos, Lagos, Markurdi, Nssuka, and PortHarcourt is 30.38, 20.16, 21.39, 24.21, 24.31, 21.49, and 21.48 dB respectively.