Radio Refractivity and frequency modulated radio signal strength were simultaneously synchronized through a self-developed frequency modulated radio signal Strength (FMRSS) and radio refractivity (RF) Meter to acquire data for this research work. The meter was tuned to Osun State Broadcasting Cooperation (OSBC) at FM 104.5 MHz to acquire data over period of 66 days from 23/11/2021 to 05/12/2021, 17/12/2021to 31/12/2021 and 01/01/2022 to 05/02/2022 respectively. The data were processed and the result viewed to infer the relationship between radio refractivity and frequency modulated radio signal strength.. Critical overview of all curves of the analysis reflects the same result that frequency modulated radio signal strength varied inversely to radio refractivity. That is, at a rising point of radio refractivity, frequency modulated radio signal strength is observed falling. Though mostly the two may have the same variation trend-lines direction, it is clearly featured in nearly all the analysis figures that a fall in radio refractivity increases the strength of OSBC frequency modulated radio signal at any point of reception during broadcasting operation. Therefore, a good reception of frequency modulated radio signal strength (FMRSS) is always achievable when all climatological parameters are at the normal states of favorable weather condition of moderate pressure, relative humidity and a fairly high temperature where radio refractivity will be at a low level for an improved frequency modulated radio signal strength in broadcasting operation. This has recommended a reasonable determination of frequency modulated radio broadcasting station site location with stronger transmitting equipment (transmitter and antenna) and appropriate antenna height positioning, that will favor low radio refractivity and strong frequency modulated radio signal strength.

Keywords : Radio, Refractivity, Signal, Strength, Frequency, Modulation, Tuned, Penetrable, Broadcasting, Operation, Climatological, Transmitting Equipment, ,Pressure, Relative Humidity and Temperature