Switched parasitic antennas and controlled reactance parasitic antennas: a systems comparison

Two antenna arrays (variable reactance and switched parasitic antennas) form part of a larger number of antenna types targeted for use as smart antennas (or adaptive antennas). A comparison is presented between the characteristics of small switched parasitic antenna arrays and varactor controlled parasitic antenna arrays. The beam widths of the two antennas are similar, but the control system and support electronics are much simpler for the switched parasitic antennas. The systems requirements of some of the applications of smart antennas are discussed in the light of the performance characteristics of these two antenna types. In most applications of these smart antennas, precise angular control of the main beam is not a critical issue for most applications. If positioning or if precise direction finding of multiple sources is a major requirement, only the varactor controlled parasitic antenna type offers this functionality.