Pattern Reconfigurable Antenna for Cognitive Radio

This paper presents a pattern reconfigurable cube antenna system that operates at 5.8 GHz (C-band). The antenna consists of four radiating units that are controlled by a reconfigurable feeding network placed in the center. Each unit is a printed four-element array antenna attached at the circumference of the rectangular feeding network to form the 3D cube structure. Therefore, the azimuthal plane can be covered by four 90-degree incremental sectors. The network is composed of a reflective SP8T RF switch and a novel microstrip line configuration that allows four output ports. The four array units are connected to these ports yielding a larger antenna array system. Thus, the reconfigurable antenna can achieve eight radiation patterns out of four radiating units. A single sector or two adjacent sectors can be scanned at any single time. The antenna maintains a well-matched condition at the frequency of interest for all the eight alternative radiation states. The antenna realized gain is greater than 9.5 dBic and 5 dBic for the case of 1 and 2 active radiating units, respectively. The antenna is suitable for cognitive radio applications thanks to the multiple radiation patterns it offers, allowing spatial filtering that can be applied in a varying electromagnetic environment.