With the worldwide application of unlicensed spectrum around 60 GHz, it has become feasible to develop communication systems with data rates in the gigabit/second range. Yet this frequency range poses challenges like high propagation loss, oxygen absorption, high antenna directivity, and limited wall penetration. To overcome these issues, a two-channel, hybrid smart-antenna system operating at the 60-GHz band has been developed by Nuri Celik and Magdy F. Iskander from the University of Hawaii at Manoa with Motorola Labs' Rudy Emrick, Steven J. Franson, and John Holmes.
Research has shown that 60-GHz signals cannot propagate through walls and diffract around objects without significant power losses. Yet such limitations also reduce interference and increase the possibility for frequency reuse. This solution uses several highly directive antennas and selects the highest-power antenna to overcome high propagation losses and provide antenna diversity to combat human shadowing. This system can detect the angle of arrival (AOA) for the incoming signal and adjust its beam pattern accordingly.
The implemented receiver comprises monolithic-microwave-integrated-circuit (MMIC) elements. By selecting the optimal twist angle to help overlap radiation patterns, the fine alignment of the transmit and receive beams is established through beamforming. See "Implementation and Experimental Verification of a Smart Antenna System Operating at 60-GHz Band," IEEE Transactions On Antennas And Propagation, September 2008, p. 2790.