where [[omega].sub.H0] is the gyrofrequency at the equator on the ground and [R.sub.T] the Earth's mean radius ([R.sub.T] = 6371 km).

For a one-layer ionosphere between the heights [h.sub.1] and [h.sub.2], the mean value of magnetic gyrofrequency is

Thus, the Earth's magnetic field is represented by a dipole model, which is eccentric (centred) in the geographic (geomagnetic) coordinate system, and the mean value of magnetic gyrofrequency is calculated as an integral of gyrofrequency referred to the geomagnetic coordinates.

The paper has deduced (18) as mean value <[[omega].sub.H]> of the magnetic gyrofrequency profile [[omega].sub.H] = [[omega].sub.H](h, [lambda]) for a one-layer ionosphere between the heights [h.sub.1] and [h.sub.2].

where the coefficients [[alpha].sub.R] and [[alpha].sub.I] are functions of the angular frequency [omega], the collision frequency [v.sub.max] (11), the atmospheric scale height H (12), the mean value of magnetic gyrofrequency <[[omega].sub.h]> (18), and the height of ionosphere bottom [h.sub.0], the refractive index across the ionosphere-neutral atmosphere boundary [n.sub.0] = n([h.sub.0]).

The QL nondeviative absorption (9), deduced in this paper, is more refined than the corresponding equation reported by Davies [1]; and, linearizing the involved equations, here are obtained the coefficients [[alpha].sub.R] and [[alpha].sub.I] as functions of the angular frequency to, the collision frequency [v.sub.max], the scale height H, the mean magnetic gyrofrequency <[[omega].sub.H]>, and the height of ionosphere bottom [h.sub.0], the refractive index across the ionosphere-neutral atmosphere boundary [n.sub.0] = n([h.sub.0]); that is [ Appendix B],

The linearized profile of complex refractive index (31a)-(31b) defined by a height of the ionosphere bottom [h.sub.0] = [h.sub.1] = 50 km and a refractive index across the ionosphere-neutral atmosphere boundary n[degrees] = n(h[degrees]) = 1 - [[epsilon].sub.max] ([[epsilon].sub.max] being the maximum allowable single step error, that is, [[epsilon].sub.max] [less than or equal to] [10.sup.-6]) is related to the collision frequency [v.sub.max] (11), the atmospheric scale height H (12), and the mean value of magnetic angular gyrofrequency <[omega].sub.H]> (18).