MIMO Antennas

Abstract

Multiple-Input-Multiple-Output (MIMO) technology has appeared to overcome the data throughput limit faced by conventional Single-Input-Single-Output (SISO) wireless communication systems. In MIMO, a significant increase in the data throughput is obtained using multiple data streams sent and received by multiple antenna elements on the transmitter and receiver ends, and this is why fourth generation (4G) wireless systems are supporting more real time multimedia applications and videos compared to older generations. The design of MIMO antenna systems is not a trivial task, and needs careful design practices. Several performance metrics have been identified for MIMO antenna systems that need to be evaluated on top of the conventional single element antenna systems. In this chapter, we will start by giving a brief background on wireless systems evolution and then highlighting the advantages of MIMO technology and its use in current 4G and future 5G wireless communication standards. The second section will treat in detail the various performance metrics that are needed to evaluate the behavior of a MIMO antenna system. The new metrics that are required for MIMO performance characterization such as the total active reflection coefficient (TARC) for multi-port antenna systems, correlation coefficient, diversity gain and channel capacity evaluation will be discussed in details. Several examples of single-band and Multi-band MIMO antenna systems are considered next with various types of antenna elements and covering a variety of wireless applications and device sizes. The chapter ends with a discussion on some of the challenges encountered in the design of MIMO antennas.