An empirical path-loss model derived from practical experiments through open space area with LOS link between two antennae, maximum extent to 30m, and less than 3meters antenna height, including tropical climate. Fresnel radius was practically affecting the model during different distances which has discussed. The model was successfully tested and compared with for distance measurement based on RSS technique which analyzed with the Fresnel radius. A calculator application is also generated to proceed the computations and it could automatically recognized if distance is an even Fresnel radius and recalculate the distance with consideration of Fresnel effects. Average error of distance measurement with use of this calculator was decreased by about 60%.