keywords: Ionosphere, very low frequency, D-region
This research presents the results of a very low frequency (VLF) signal received by a VLF receiver at the University of Ilorin, Ilorin (ILR) station (4.68° N, 8.49° E), from 23rd of January 2021 to 17th May 2021. Using a square-shaped loop antenna (Rx) of 7.2 meters perimeter, the VLF receiver tracks transmitting signals from three selected VLF transmitter stations namely VTX (19.2 kHz), India, NWC (19.8 kHz), Australia and GBZ (19.5 kHz), United Kingdom. A comparison was made with the VLF amplitude signal with an electron density of the D-region that was obtained from the International Reference Ionosphere (IRI) model. The result of the work shows a period of sunrise time (SRT) and sunset time (SST) on the VLF amplitude signal for some selected days. The solar quiet day morphology at the ILR station reveals that the VLF signal strength is high at night than in the daytime. This shows evidence of 24 hours of solar radiation and the signature of the appearance and disappearance of the D-region.