Dual-band electro-optically steerable antenna

Abstract

The ability to obtain dynamic control over an antenna radiation pattern is one of the main functions, desired in a vast range of applications, including wireless communications, radars, and many others. Widely used approaches include mechanical scanning with antenna apertures and phase switching in arrays. Both of those realizations have severe limitations, related to scanning speeds and implementation costs. Here we demonstrate a solution, where the antenna pattern is switched with optical signals. The system encompasses an active element, surrounded by a set of cylindrically arranged passive dipolar directors, functionalized with tunable impedances. The control circuit is realized as a bipolar transistor, driven by a photodiode. Light illumination in this case serves as a trigger, capable of either closing or opening the transistor, switching the impedance between two values. Following this approach, a compact half-a-wavelength footprint antenna, capable to switch between 6 dBi directional patterns within a few milliseconds latency was demonstrated. The developed light activation approach allows constructing devices with multiple almost non-interacting degrees of freedom, as brunched feeding network is not required. The capability of MHz and faster switching between multiple electromagnetic degrees of freedom open pathways to new wireless applications, where fast beam steering and beamforming performances are required.