Accurate optimization technique for phase-gradient metasurfaces used in compact near-field meta-steering systems

Area of Science:

• Electromagnetics and Applied Physics
• Antenna Theory and Design
• Metamaterials and Nanophotonics

Background:

• Near-Field Meta-Steering (NFMS) is an emerging antenna beam-steering technology.
• Traditional NFMS designs overlook the oblique incidence on the upper metasurface, leading to signal leakage.
• Grating and side lobes are inherent issues in beam-steering systems.

Purpose of the Study:

• To propose an accurate optimization method for metasurfaces in NFMS systems.
• To reduce signal leakage by suppressing grating and side lobes.
• To improve directivity and overall performance of NFMS antenna systems.

Main Methods:

• Detailed design and optimization approach for both upper and lower Phase-Gradient Metasurfaces (PGMs).
• Development of an accurate optimization methodology accounting for oblique incidence.
• Experimental validation of the proposed 2D compact NFMS design.

Main Results:

• The proposed NFMS system exhibits higher directivity (1.4 dB higher broadside directivity) compared to conventional designs.
• Significantly lower side-lobe (-4 dB lower) and grating lobe levels across the entire scanning range.
• Experimental validation shows excellent agreement between predicted and measured beam-steering patterns.

Conclusions:

• The accurate optimization method effectively suppresses signal leakage in NFMS systems.
• The proposed system offers superior directivity and reduced side-lobe levels.
• Truncated PGMs are compatible with low-gain antennas, showing promise for wireless backhaul and future antenna hardware.