Fractal-Shaped Reconfigurable Antennas

With the tremendous advancements in wireless communications, there is an increasing demand for miniature, low-cost, easy-to-fabricate, multiband and wideband antennas for use in commercial communications systems. As a part of an effort to further enhance modern communications systems technology, researchers have been studying different approaches for creating novel and innovative antennas. The fact that different wireless standards, such as UMTS, WLAN and WiMAX, use different operation bands, pushes the need for terminal antennas that are multiband and/or wideband. The antennas should also be well-suited in terms of cost, size, radiation patterns, gain and ease of integration in the circuit boards of communication devices. Microstrip antennas have received increasing attention in satellite and communications applications because of their low profile, small size, light weight, low cost and ease of fabrication. Their simple feed methods, especially microstrip-line and coplanar waveguide (CPW) feeds, make them compatible with wireless communication integrated circuitry. In this chapter, fractal-shaped and reconfigurable microstrip antennas are discussed. The space-filling and self-similarity properties of fractal geometries, from an antenna engineering perspective, are presented. Moreover, the recent techniques used in microstrip antennas with frequency-, polarizationand pattern-reconfigurability are surveyed. A separate section will focus on hybrid antenna design approaches, which combine fractal shapes and electronic reconfigurability.