This chapter provides a conceptual description of reconfigurable antennas, a discussion on reconfigurable antenna parameters, and practical considerations for their design. Case studies in both reconfigurable large and small aperture antennas serve as examples of the kinds of functionality that can be achieved with a very diverse set of topologies and technologies. Finally, advanced reconfigurable antenna applications for the future are discussed. Reconfigurable antennas provide additional functionality and flexibility at the expense of increased complexity. Innovative designs can incorporate state-of-the-art technologies to interact with the radiating mechanism and facilitate reversible changes. Reconfigurable antennas can provide new degrees of freedom that will affect how communication, sensing, and radar systems are specified and designed in the future. New approaches may require interdisciplinary solutions to the design of electrical, mechanical, and material components, as well as decision and control circuitry and protocols, for these systems. This new level of integration with system operation has the potential to dramatically increase system performance while providing new incentives to reduce complexity and cost.
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