Study and performance analysis of low profile antenna arrays for MIMO WLANs applications

The main objective of the research project lies in implementing a low-profile multi-antenna system suitable for integration on portable devices supporting the new IEEE 802.11n standard for wireless communications. The reduction of the overall dimension and the use of antennas designed ad-hoc, likely to be in microstrip technology, lead to the study of innovative solutions. In fact, commercial 802.11n devices make use of a linear array of wire dipoles having large dimensions and spaced of about a wavelength, for a carrier frequency equal to 2.4 GHz. Hence, the adopted antennas are discrete stand-alone irradiating elements, while with the present project we aim to implement integrated irradiating elements. Moreover, in some existing devices where a reduced size is a fundamental requirement (for instance the use of MIMO on PCI boards), the used dipoles are very close to each other and then severe electromagnetic coupling negatively impacts on the achievable diversity order. Thanks to the study, design, simulation and testing as planned by the project, it will be possible to understand the causes and effects due to mutual coupling with regard to the adopted technology and system performance. The implementation of IEEE 802.11n transmitters and receivers is made possible by the research and development in the areas of information theory and signal processing. However, the antenna equipment has not been improved with similar gains. Therefore, there are wide margins of action for making existing technology better deriving from some recent theoretical results appeared in the literature about antennas and wireless propagation.