研究目的
Designing a high-efficiency planar reflectarray with small size for generating orbital angular momentum (OAM) waves at microwave frequencies, capable of converting arbitrary polarized waves to OAM waves with desired mode number and beam direction.
研究成果
The proposed reflectarray achieves high efficiency (22.6%), high gain (15.4 dBi), narrow divergence angle (9°), high purity, good stability, polarization insensitivity, planar structure, and easy fabrication. It successfully generates OAM beams with modes l=1,2,3,4 at various directions, demonstrating its effectiveness and superiority over previous designs in terms of size and efficiency.
研究不足
The smaller aperture size leads to a relatively lower gain compared to larger antennas, and the divergence angle, while narrow, is wider than some designs with larger size. The design is optimized for 5.8 GHz and may not be directly applicable to other frequencies without modification.
1：Experimental Design and Method Selection:
The reflectarray is designed using a unit cell composed of two concentric rings to achieve a 360-degree phase shift range. The overall design is based on phase compensation to generate spiral phase wavefronts for OAM beams. Simulations are performed using CST Microwave Studio.
2：Sample Selection and Data Sources:
The reflectarray consists of 10x10 units with a total size of 200x200 mm2 (3.87λ0 x 3.87λ0). The unit cell size is 20x20 mm2 (0.38λ0 x 0.38λ0). Data is sourced from simulations and experimental measurements.
3：87λ0 x 87λ0). The unit cell size is 20x20 mm2 (38λ0 x 38λ0). Data is sourced from simulations and experimental measurements.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: A horn feeder with 3dB beamwidth of 27.2°, F4B substrate with thickness 0.508 mm and permittivity 2.25, metal ground, and air gap of 5 mm. The prototype is fabricated and tested.
4：2°, F4B substrate with thickness 508 mm and permittivity 25, metal ground, and air gap of 5 mm. The prototype is fabricated and tested.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: The reflectarray is excited by a spherical wave from the horn feeder. Phase distributions are calculated using MATLAB based on equations for phase delay and compensation. Measurements include near-field and far-field radiation patterns, phase distributions, and OAM purity analysis.
5：Data Analysis Methods:
Data is analyzed using Fourier transforms for OAM spectrum weight calculation, and radiation patterns are compared between simulation and measurement.
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