Broadband high-efficiency 3-bit coding metasurface in transmission mode based on the polarization conversion...

Area of Science:

• Electromagnetics
• Metamaterials
• Antenna Engineering

Background:

• Transmissive focusing metasurfaces (TFMs) face challenges with limited operational bandwidth and aperture efficiency.
• Simultaneously improving both bandwidth and efficiency in TFMs is a significant hurdle in the field.

Purpose of the Study:

• To introduce a novel multi-state coding metasurface designed to overcome the bandwidth and aperture efficiency limitations of traditional TFMs.
• To demonstrate a TFM with enhanced radiation characteristics through combined system-level and element-level synthesis approaches.

Main Methods:

• Employed a multi-frequency phase synthesis (MFPS) approach for system-level design, optimizing phase error across the operational band.
• Utilized a polarization-controlled transmission (PCT)-based wideband technology at the element level, featuring a subwavelength non-resonant design with C-shaped metallic patterns on two dielectric layers.
• Implemented an optimization algorithm to balance gain variations and aperture efficiency.

Main Results:

• The developed metasurface element achieved high transmission amplitude (>0.9) for rotated polarization across the 12.3–16.5 GHz band.
• A fabricated 25x25 element TFM demonstrated a 1-dB gain bandwidth of 29% (12.3–16.5 GHz).
• The maximum measured aperture efficiency reached 53.6% at 12.8 GHz.

Conclusions:

• The proposed multi-state coding metasurface effectively enhances both frequency bandwidth and aperture efficiency.
• The novel TFM design, utilizing MFPS and PCT-based technology, represents a significant advancement in broadband, high-efficiency metasurface applications.