Antenna space diversity and polarization mismatch in wideband 60GHz-Millimeter-wave wireless system

This paper presents a study on the fading behavior in wideband 60 GHz-Millimeter-wave (MMW) wireless system. The evaluation is carried out based on a two-ray propagation model, with considering the large propagation loss of the multi-reflected waves other than the first reflected wave at 60 GHz-millimeter-wave. The study focuses on the strong fading effect due to the large variation of antenna location compared to the short wavelength (about 5 mm) and the wide frequency range (about 9 GHz) in such MMW wireless system. The influence of the polarization mismatch of antenna is also investigated. To reduce the fading, we employ the technique of space diversity by introducing two or more antennas in receiving side. We perform an optimization of the locations (heights) for these antennas. From the simulation results, we obtain some optimal heights with which the fading effect can be reduced in less than 3 dB. The simulation results also reveal how the polarization mismatch, in two different cases of antenna rotations, influences the system performance, and how space diversity reduce the fading as well. The antenna used in simulation is a planar patch antenna which is considered suitable for portable wireless handset. The radiation pattern is obtained from electromagnetic simulation. This paper demonstrates that by employing multiple antennas with optimized antenna locations can significantly reduce the fading for the 60 GHz-MMW wireless system.