The prediction of the magnetic field intensity of VLF waves in the upper ionosphere generated by a ground transmitter is investigated using a latitudinally dependent model of the ionosphere that includes only electrons as charged particles. The behavior of the wave in the lower ionosphere is analyzed using a full-wave computer program developed by Scarabucci. The attenuation in the neutral atmosphere leaky waveguide is found using the results of that program. Above the E region the WKB approximation is used to find the ray trajectories. Based on these assumptions, a mapping of the wave magnetic field intensity at an altitude of 500 km for a night transmission of the NAA station is found. The theoretical predictions are compared with some data obtained from the OGO-4 satellite.