Beam-steering by a phase-transition metal-based 1-bit programmable metasurface

Abstract Here the beam-steering mechanism is demonstrated using a 1 bit coded metasurface at 2.5 THz. Each unit cell of the metasurface is loaded with vanadium dioxide (VO 2 ) which undergoes phase transition upon excitation by an external stimulus. The electrical and magnetic properties of VO 2 change as the transition takes place from insulator to metal resulting in a reflection phase change of 180°. When the metasurface is excited by a microstrip patch antenna placed at a focal distance above it, the reflected beam is directed at an angle of 22°, as a result of anomalous reflection. By changing the coding pattern of the metasurface, the reflected beam is redirected at −22°. Four different coding patterns have been proposed to depict beam-steering action by the metasurface. The maximum gain registered by the reflect-array integrated antenna is 21 dBi at 2.5 THz. THz beam steering assists in forming directional beams which can be deployed in wireless transmission of THz waves.