Optical control of pattern-reconfigurable planar antennas

This paper presents a pattern-reconfigurable planar antenna that is optically controlled to switch in and out various composite printed circuit radiators in each of the quadrants. The designed antenna is able to generate a single omnidirectional or four directional patterns by switching between the microstrip elements, maintaining a good impedance matching over the entire 2.4 GHz WiFi band. By using commercially available optical devices, two different strategies were explored for the optical control: i) PIN photodetectors based switching, and ii) a photo-transistor controlled RF PIN diodes for switching. Different advantages and limitations of each technique are discussed, when implementing as single-pole-single-throw RF switches in the proposed composite antenna. The antenna's characteristics are reported, where a matched input impedance and radiation patterns are achieved over WiFi frequency band.