Compact Antennas for Wireless Communications and Terminals: Theory and Design

Chapter 11Introduction to Antenna Diversity ¹

 

 

 

11.1. Benefits of antenna diversity

Modern telecommunication systems need to offer ever-improving performances in terms of coverage, reception quality, data rate, etc. Research has suggested some innovative techniques that jointly exploit multiple antennas for the transmission and/or reception of information. These multiantenna techniques offer some excellent perspectives on optimizing wireless communications, and in recent years we have seen an explosion in the number of antennas in use in wireless devices. Domestic Wi-Fi networks or even portable television receivers are widespread examples of systems that exploit antenna diversity. Some examples of these are shown in Figure 11.1.

The space available for antennas is more and more limited, as the trend is for terminals that are compact, thin, and light. Nowadays, antenna designers have to devise miniaturized multiantenna systems, while limiting interference between the concerned antennas. This chapter forms an introduction to the issues in antenna diversity. It presents the primary concepts and useful tools for optimizing multiantenna systems. First, we will discuss signal degradations due to the multipath propagation channel. We will present the principles of the multiple reception antennas that compensate these effects. Then we will see how the performance of multiple antennas can be measured against criteria based on the radioelectrical characteristics. Finally, we will show ...