This work presentes an experimental study of diversity techniques used to combat the effect of channel fading on mobile cellular systems. A comlete theoretical review have shown the main existent diversity methods and the techniques used to combine the different branches of diversity used. A mobile laboratory was assembled and an extensive measurement campaign was carried out on an urban region of the Rio de Janeiro city. Due to the perspectives of personal communication and third generation cellular systems to be deployed, frequecies on the 900 MHz and 1800 MHz band were used on this work. Hence, a comparision between diversity gain on these frequencies was obtained. Results of space and polarization diversity have shown similar behavior in terms of gain. An important contribution of this work was on the effects of a combined space polarization diversity where the crosspolar ports of two spatially spaced antennae were considered.