High-speed (2-100 Mb/sec) wireless data communication - whether land- or satellite based - faces two challenges: (1) high error rates caused by interference and unpredictable environments, and (2) limited signal processing capability and battery life at the portable unit. 'Intelligent' or 'smart' antenna systems can help meet these challenges. Current 'smart' systems reside mainly at base stations and rely largely on signal processing to achieve their goals. However, the performance gains of base station intelligence are constrained by the portable units-the weakest components of the system. The idea of a 'smart' system for a portable unit has received little consideration due to the perceived limitations imposed by reliance on a single, non-adjustable antenna. However, new developments in antenna capabilities that allow autonomous responses to local operating conditions while remaining practical and cost-effective have the potential to greatly improve the reliability of high-speed wireless links.