Abstract: “Friis equation describes relationship between power leaving transmitting antenna and power delivered by receiving antenna; we present in this paper a modification of the Friis Free Space Attenuation equation to model propagation in urban scenarios. We adjust it changing the exponent value of 2 and adding an arbitrary attenuation factor to fit regression curves obtained from measurements made in Mexico City in the frequency of 3.3 GHz, after find scenarios with similar characteristics in different places of Mexico City.”

Keywords: Modification of Free Space Attenuation, Measurement of urban attenuation, WiMAX.