Abstract : We are currently seeing a very important development for radiocommunication in urban areas and in buildings including the generalization of WLAN networks and the increase of the number of mobile devices that can connect these networks. In urban or indoor environment, these communications are altered by multiple reflections leading to multipath fading on RF signal. Antenna diversity provides an efficient means to improve the radio link in these environments. Diversity Gain can be obtained by the recombination of uncorrelated signals provided by different antenna systems which can implement polarization, spatial or pattern diversity techniques. In SIMO (Single Input Multiple Output) context, we therefore worked on different diversity antennas structures potentially usable in mobile communicating objects. To compare their performance, we have developed and implemented a theoretical methodology for diversity evaluation by introducing new concepts like the referenced diversity gain. This methodology allows choosing an optimized antenna system for a given application. This methodology has been validated in the case of several practical applications. In addition to our study on theoretical tools, we developed a test bench in order to quantify the radio link improvement bring by an antenna diversity system in terms of bit error rate. Our experimental method for diversity gain evaluation involves a measurement device using realistic RF signals with digital modulations. Thus, viewed in this light, it differs from experimental methods proposed in recent previous works. Finally, experimental procedure and first measurement results are detailed in this document.