Multi-Layer Metal Only Orbital Angular Momentum (OAM) Reflectarray Electromagnetic Waves

Design and analysis of a multilayer metal-only reflectarray antenna is presented in this paper to generate orbital angular momentum (OAM) waves. Three distinct designs of the multilayer metal-only reflectarray are proposed to achieve the three OAM modes—modes 0, 1, and 2-at an operating frequency of 10 GHz. The antenna structure comprises a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$20\times 20$</tex> array of elements arranged over an area of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$40\times 40\ \text{cm}^{2}$</tex>. Variations in the reflection coefficient, both in magnitude and phase, are accomplished by adjusting the length of each internal fingers in the elements. The characteristics of the OAM antenna for modes 0, 1, and 2 are analyzed at the operating frequency of 10 GHz. Additionally, the near-field phase distributions are examined for all modes at a distance of 30 mm from the antenna surface. To validate the performance of the proposed OAM reflectarray antenna, numerical simulations are conducted using CST Microwave Studio. The results demonstrate that the designed antenna holds significant potential for applications in reconfigurable OAM-based wireless communication systems.