Abstract. The large-scale high-latitude F-region modification by high power radio waves is investigated using a numerical model of the convecting high-latitude ionosphere developed earlier. Simulations are performed for the point with geographic coordinates of the ionospheric heater near Tromsø, Scandinavia for autumn conditions. The calculations are made for distinct cases, in which high power waves have different frequencies, both for nocturnal and for day-time conditions. The results of modeling indicate that the frequency of HF waves ought to influence significantly the large-scale F-region modification by high power radio waves in the high-latitude ionosphere.Key words. Ionosphere (active experiments; modeling and forecasting; plasma temperature and density)