IJMDIC (2020) 1–11 © Journals Pub 2020. All Rights Reserved Page 1 International Journal of Microelectronics and Digital Integrated Circuits ISSN: 2456-3986 Vol. 6: Issue 2 www.journalspub.com Development of a Ray-tracing Program and its Application in Characterizing the Range of HF Radio Propagation in the Equatorial Ionosphere Sulaiman M.Y. 1, *, Okoh D.I. 2 , Joshua B.W. 3 , Rabiu A.B. 4 1,2,3,4 Research Scholars 1,3 Department of Physics, Kebbi State University of Science and Technology, Aliero, Nigeria 2,4 Space Environment Research Laboratory, Centre for Atmospheric Research, NSRDA Abuja, Nigeria ABSTRACT A ray tracing program which is an algorithm that can be used to describe the complex nature of the ionosphere has been developed using locally available resources. The International Reference Ionosphere (IRI) Ionospheric Model were incorporated into the program for evaluating electron density values. Complex refractive indices of the ionosphere were generated using Appletone-Hartree formula with no collision and magnetic field effects. The program applies Snell’s law of refraction in generating signal’s refraction. 2-D ray coordinates were generated and ray path was plotted. The illustration in the application of the program was done using an assumed transmission of 6.957 MHz radio frequency from Abuja (7.38 o E, 8.99 o N) in the direction of Lagos (6.52 o N, 3.38 o E), Nigeria. Results provided amongst others includes, distribution of electron density (Ne) for the day and night time; minimum value of Ne at night (0:00 UT), ascending in the morning (6:00 UT), maximum at or close to noon (12:00-14:00 UT) and descending in the evening (18:00 UT). Rays travel farther distance in the solstice seasons than in the equinox seasons. Radio waves leaving the earth at high transmission angles above the horizon may receive only slight bending due to refraction, and are lost to outer space. It is hoped that the program will find immense application in High Frequency (HF) radio communication industries, research industries, aviation industries, and other industries that make use of Earth-Space systems. Keywords: Electron density, Ionosphere, Ray Tracing, Radio Waves. *Corresponding Author E-mail: smyushau@gmail.com INTRODUCTION The ionosphere is an important layer in the study of radio wave propagation. Both Government and Non-governmental Organizations make use of the ionosphere in making contact over long distance communications. The ionosphere starts at an altitude of about 50 km above the Earth’s surface and extends up to about thousands of kilometres. It consists of plasma which is produced by the photoionization of thin upper atmospheric gases by UV rays and photons of short wavelength from the sun [1]. The equatorial region is a region of ionosphere which extends from the magnetic equator to about ±25 o of magnetic latitude and is very dynamic in nature. At this region, the