THE EFFECT OF A TRANSVERSE IRREGULARITY ON THE ELECTROMAGNETIC-FIELDSEXCITED BY VLF TRANSMITTERS AT IONOSPHERIC HEIGHTS IN THE EARTH-IONOSPHERE WAVE-GUIDE NEAR THE TERMINATOR

The effect of a transverse irregularity on the eigenvalues of the radi al operator of the problem for the Earth-ionosphere irregular spherica l waveguide is estimated for the case that the propagation path is in the neighbourhood of the terminator. The method is based on the soluti on of the horizontal eikonal equation for the complex phase which depe nds on the angular coordinates. The corrections defined in the first a pproximation allow us to evaluate the effect of the transverse irregul arity on the fields excited in the waveguide by VLF transmitters locat ed in the low ionosphere and at satellite altitudes. (C) 1997 Elsevier Science Ltd.