Beam Steering Using Momentum-Reconfigurable Goubau Meta-Line Radiators.

Spoof/designer surface plasmon polaritons (SPP) and Goubau line belong to the same category of single-conductor surface waveguide. They feature easy integration and high field confinement capability, and hence are good candidates for wave guiding and radiating at terahertz frequencies. Here, we propose a momentum-reconfigurable Goubau meta-line radiator that is capable of digitally steering its beam at a fixed frequency, in contrast to conventional SPP or Goubau line radiators relying on changing frequencies to steer beams. By periodically loading switchable meta-lines with ON and OFF states along the Goubau line, the modulation period and hence the momentum of Goubau line radiators can be dynamically controlled. The proposed Goubau line radiator is able to steer the main beam at a given frequency by independently switching ON or OFF each unit cell. As a proof of concept, we use line connection and disconnection to mimic ON and OFF state of the switch, respectively. Several radiators, representing different switching coding combinations, are fabricated and experimentally validated. Although this momentum-reconfigurable Goubau meta-line radiator is demonstrated at microwave frequency, it can be easily extended to terahertz frequencies.