Numerical method for calculating LF sky-wave, ground-wave and their resultant wave field strengths

A wave hop method for calculating field strengths of sky-waves, the ground-wave and the resultant of those wave components at frequencies from 60 to 500 kHz up to 4000 km is presented. The diurnal and distance variations of resultant field strengths predicted with the method for various transmission conditions show good agreement with those measured.