Measurement of Electric Field Strength to Determine the Coverage Areas of F.M. Radio Signals in Niger State

Abstract

At the VHF band (30 MHz – 300 MHz), radio propagation is usually by ground waves which consist of direct wave, ground reflected wave and surface wave. These radio signals are affected by the electrical parameters of the ground, curvature of the earth surface, height of the antenna above earth’s surface and weather conditions in the troposphere. The electric field strength of radio signals decreases with increase in distance from the transmitting antenna. In this work, measurement of electric field strength of Frequency Modulated (FM) radio broadcast signals from two FM radio stations - Crystal FM on 91.2 MHz and Power FM on 100.5 MHz in Niger State were carried out in all the 25 Local Government Areas in Niger State, using a Digital Signal Level Meter, GE-5499, covering the signal range of 30 – 120 dBμV. The longitude, latitude, altitude and also distance from the reference point (i.e location of the transmitting antenna) were measured at every location using a Global positioning System (GPS), GPS-72, personal navigator. These measurements were carried out at the onset of rain season (May). The parameters obtained were used to determine the coverage areas of FM radio signals in Niger State. The result obtained showed that; 16% of the Local Government Areas (LGAs) receive Grade A (signal level _ 60 dBμV) quality of service from Power FM while 24% receive Grade A quality of service from Crystal FM, 48% of the LGAs receive Grade B (signal level > 30 dBμV and 0 dBμV and _ 30 dBμV) quality of service from both Power FM and Crystal FM, 12% of the 25 LGAs are completely out of the coverage areas of Crystal FM and Power FM. The configuration of FM radio transmitters in Niger State does not give optimum coverage in the State