A method for estimating the electric field strength associated to a radio wave emitted by an electromagnetic source of a cellular radio communication network within an area. The method includes: identifying a set of obstacles; determining at least one of: a direct visibility polygon of points in line of sight with the source; a reflection visibility polygon of points reachable by the wave after reflection by the obstacles; a diffraction visibility polygon of points reachable by the wave after diffraction by the obstacles. The visibility polygons are associated to respective values of the electric field computed therein. The method further includes: subdividing the area into pixels; for each pixel, determining if it belongs to at least one of the visibility polygons; and in the affirmative, determining the electric field strength at the pixel as a value proportional to the electric field computed at the at least one visibility polygon.