A universal chart for use in relating ionospheric absorption to phase path and group path

The absorption of a radio wave in the ionosphere can be approximated by
A = \frac{\omega}{c}\frac{1}{2}\int\frac{Z(\mu' - \mu)}{1 + g} cos \alpha ds
, where the integral is along the ray that exists when the normalized collision frequency
Z = 0, \mu'
and
\mu
are the group and phase refractive indices, respectively, and
\alpha
the angle between the wave normal and ray direction. Graphs are presented from which
g
can be obtained for any values of the ionospheric plasma parameters
X
and
Y
.