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Angular momentum characterizes an object's rotational motion and is defined as the moment of its linear momentum about a specified point O. When a particle moves along a curved path in the x-y plane, the scalar formulation calculates the magnitude of its angular momentum, utilizing the moment arm (d), representing the perpendicular distance from point O to the line of action of the linear momentum. Despite being scalar in formulation, angular momentum is inherently a vector quantity. Its...
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A Small-Divergence-Angle Orbital Angular Momentum Metasurface Antenna.

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This study introduces a novel metasurface antenna for generating orbital angular momentum (OAM) beams with a reduced divergence angle. The compact design simplifies structure and enhances practical OAM applications.

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Area of Science:

  • Electromagnetics and antenna engineering.
  • Metasurface applications in wave manipulation.

Background:

  • Orbital angular momentum (OAM) beams are of significant interest for advanced communication systems.
  • Existing OAM antennas suffer from complex structures, low efficiency, and large divergence angles, hindering practical use.
  • The divergence angle of OAM beams is a critical parameter with limited research focus.

Purpose of the Study:

  • To propose and validate a metasurface antenna for generating OAM beams with a small divergence angle.
  • To address the limitations of conventional OAM antennas, particularly their divergence characteristics.
  • To provide a compact and efficient solution for OAM beam generation.

Main Methods:

  • Design of a metasurface antenna utilizing circular arrangement and phase gradient.
  • Theoretical analysis and derivation of antenna parameters.
  • Validation through electromagnetic simulations and experimental measurements.

Main Results:

  • The proposed metasurface antenna achieves a simplified structure and a reduced divergence angle for OAM beams.
  • A high transmission coefficient was observed for the metasurface antenna.
  • Experimental and simulation results confirmed the theoretical predictions.

Conclusions:

  • The developed compact metasurface antenna effectively generates OAM beams with a small divergence angle.
  • This work offers a promising pathway for the practical implementation of OAM technologies.
  • The simplified structure and improved performance overcome key limitations of current OAM antennas.