| With the growing needs of its users, the wireless communications field has been undergoing unprecedented development. Even well diversified, those needs in communications services are generally great consumers of bandwidth. This justifies the use of high frequency bands that could allow the transmission of large information throughputs through telecommunications networks. Recently, many hopes are levied on the 60 GHz frequency band because of its large 7 GHz bandwidth (57-66 GHz) and the expected high data rate to support several types of services and possible applications. It seems to be a good candidate for future communications systems. However, given the encountered difficulties in the channel, the received signal is rarely found without undergoing deformations such as caused by path loss, shadowing and multipath fading.;In a real wireless communications situation, the antennas are often in a non line of sight situation. With obstacles in the transmission path, it is necessary to study relevant propagation parameters to characterize the channel, so we can design adequate systems ensuring a good quality of service. Thus, when it comes to a wireless underground channel, characterization is complex because of the random nature of the environment that may cause significant effects in terms of diffusion, diffraction, reflection, etc.;Conducted in collaboration with the LRTCS-UQAT, this thesis is part of a larger research project aimed at optimizing the design of new wireless communications systems in underground environments. Based on a measurement campaign in the CANMET mine in Abitibi Temiscamingue in the north of Quebec, Canada, this study is focused on 60 GHz wideband underground channel characterization in LOS conditions. Even though most of the real wireless communications cases antennas are not necessary in NLOS, this study has been done in LOS conditions and the stationnarity of the channel has been maintained. That choice is explained by a weak received signal obtained when antennas are in NLOS. Also, the hostile nature of the mine environment leads to strong attenuation of the signal. The path loss exponent, the shadowing effect, the average received power and the rms delay spread are the parameters extracted from the measurement campaign.;With different antenna combinations and polarizations, the results of this current study, when compared with previous ones done in the same or in different environments, should serve as a dashboard for specialized designers of underground wireless communications equipment. |
