Radio waves in the ionosphere were first published in 1961. Since then there have been many major advances that affect the study of radio propagation and three in particular.
- The first is the use of space vehicles and rockets, which have enabled the top side of the ionosphere to be studied and have revealed the earth’s magnetosphere and magnetotail.
- The second is the advance of the subject Plasma physics which has transformed our knowledge of the physical processes in ion plasma.
- The third is the use of computers, large and small which by removing the need for laborious calculations.
Radio receivers are often used in rockets and satellites within the ionosphere or magnetosphere. It is thus important to be able to study the spatial distributions of the electromagnetic field within. At higher frequencies, this can be done by ray tracing. At lower frequencies it is necessary to use the computed solution of the governing differential equations.