An obstacle can be considered isolated if there is no interaction between the obstacle itself and thesurrounding terrain. In other words, the path attenuation is only due to the obstacle alone without anycontribution from the remaining terrain. The following conditions must be satisfied:– no overlapping between penumbra widths associated with each terminal and the obstacle top;– the path clearance on both sides of the obstacles should be, at least, 0.6 of the first Fresnelzone radius;– no specular reflection on both sides of the obstacle.