Various Antenna Design Schemes in Recent MIMO Wireless System
Multi-input Multi-output (MIMO) and diversity technology have recently attracted considerable attention in both industry and academia due to high data rates and high spectrum efficiency. The multiple/MIMO techniques can increase the number of antennas on the transmitter and/or receptor side of the wireless link without needing additional power or spectrum in a rich scattering environment. However, the correlation coefficients between MIMO antenna elements are usually very high, due to the small space of mobile devices and the overall efficiency of MIMO elements would be severely degraded by the interconnected connections. Furthermore, the human body causes high electromagnetic waves losses. The presence of users in actual applications could significantly reduce the total efficiency of the antenna, and the correlations of MIMO antenna systems are also greatly affected. This chapter examines the performance of some basic MIMO antennas as well as the recent technologies to improve the performance of MIMO antennas on mobile devices and terminals. In mobile terminal applications, the interactions between MIMO antennas and human body are also targeted.