Reconfigurable Holographic Transmit Reflect Array with OAM Vortex Wave

Abstract

A novel plasma-based metamaterial holographic reflectarray/transmitarray antenna that can both reflect and transmit incoming electromagnetic waves is presented in this paper. The proposed design achieves a high gain of 30 dBi at 16 GHz, demonstrating its effectiveness for advanced communication applications. Plasma is a reconfigurable material that enables the development of a reconfigurable antenna. The designed antenna is made up of a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$21\times 21$</tex> array of unit cells, covering a total area of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$25.2\times 25.2\ \text{cm}^{2}$</tex>. The plasma unit cell functions in two modes: reflection and transmission. The radiation properties of the reflectarray, transmitarray, and their combined operation are analyzed. In addition, vortex waves with tunable orbital angular momentum (OAM) are produced by designing a holographic transmitarray and reflectarray from a plasma-based metamaterial. By adjusting the ionization level of the plasma within each unit cell through the applied DC bias voltage, the 360° transmission phase and a 327° reflection phase are obtained. The OAM waves with tunable modes including <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$l=1,2,3$</tex> is generated by arranging the metamaterial element into a holographic transmitarray. The simulation result presents the proposed design with good performance, providing a feasible way to generate and process OAM vortex waves efficiently. Beam steering for OAM vortex waves in different directions from 0° to 30° is achieved by modifying the plasma frequency of the array elements at f= 16 GHz for transmitarray and reflectarray. In the case of the transmitarray, two beams are generated at angles (10°, 90°) and (-10°, 90°).