Antenna diversity array design for mobile communication systems

Diversity reception is a technique in radio communications to provide better spectrum efficiency at the cost of an extra set of antennas. The basic requirement of antenna diversity is to have more than one way to receive incoming electromagnetic waves provided usually by a multi-element antenna configuration. The reception modes should be as uncorrelated as possible since the received signal to interference ratio can be optimized on the basis of the correlation properties of the signals. A well known example of antenna diversity usage is the reduction of signal fading in multipath environments such as downtown areas in large cities or indoor environments. Antenna diversity in its various forms and implementation techniques is found to be a very useful and cost-effective addition to many narrow bandwidth TDMA/FDMA-systems, as well as low chip-rate CDMA systems. Applications of diversity reception include for instance cellular telephone networks and wireless local area networks (WLAN).