Design of High-Gain Multi-Band Circularly Polarized Bi-Layered Metasurface Patch Array Antenna
Research on the Design of High Gain Multi-band Circularly Polarized Bi-layered Metasurface Patch Array Antenna
Academic Background and Research Motivation
Terahertz (THz) band communication has received widespread attention in recent years due to its potential to expand bandwidth in wireless communication systems. However, the application of terahertz systems faces many challenges, among which signal attenuation and insufficient bandwidth are the main issues. To solve these problems, designing high-performance antennas becomes crucial. Although traditional microstrip antennas have a simple design, their narrow bandwidth and low gain limit their application in the terahertz band. Additionally, circular polarization (CP) technology can effectively reduce polarization mismatch between transmitters and receivers, thereby improving communication quality.
To address the above challenges, researchers proposed a new design combining dual-feed patch array antennas with bi-layered metasurfaces. This design aims to achieve high gain, multi-band circular polarization characteristics, and enhance performance through optimized antenna structures and material selection. The goal of this research is to develop an efficient antenna capable of operating across multiple frequency ranges to meet the needs of future 6G communications, drug detection, and security systems.
Paper Source and Author Information
This paper was co-authored by Mona Pourhosseini, Saughar Jarchi, Pejman Rezaei, and Zahra Ghattan Kashani. The authors are affiliated with the following institutions: - Imam Khomeini International University (Qazvin, Iran) - Semnan University (Semnan, Iran) - K.N. Toosi University of Technology (Tehran, Iran)
The paper was published in 2025 in the journal Optical and Quantum Electronics, article number 155, DOI: 10.1007/s11082-025-08068-5.
Research Methods and Experimental Procedures
a) Research Workflow and Experimental Design
This study is divided into the following steps:
1. Antenna Array Design
The study first designed a broadband dual-feed patch array antenna. The antenna consists of two patches of different sizes, with the central patch measuring 40 μm × 40 μm and the side patches half that size (20 μm × 20 μm). This design allows the antenna to resonate at two different frequencies. The antenna uses a silicon substrate (thickness 6 μm, relative permittivity 11.9) and was electromagnetically simulated using CST Microwave Studio software.
To achieve circular polarization characteristics, the study made improvements to the patches: - A cross-shaped slit and crescent-shaped arc were cut into the central patch. - A cross-shaped slit was cut into the side patches.
These geometric modifications help convert linear polarization to circular polarization, and the length of the slits and radius of the arcs were optimized through parametric analysis.
2. Bi-layered Metasurface Design
The study designed a bi-layered metasurface structure to further enhance the circular polarization characteristics of the antenna. The metasurface consists of two layers: - The bottom layer consists of four connected square units. - The top layer forms an “8” shaped pattern, consisting of two interconnected square loops.
The dimensions of the metasurface unit cells were optimized with specific parameters: a = 4.5 μm, a1 = 2.5 μm, b = 1.6 μm, b1 = 1 μm, lm = 17.5 μm. The metasurface material is silicon dioxide (SiO₂), with a thickness of 0.75 μm, to achieve a low-profile design.
3. Integrated Structure and Testing
The final structure places the bi-layered metasurface directly above the patch array antenna. The entire antenna system consists of four layers: ground plane, patch array, bottom metasurface, and top metasurface. Each layer is isolated by silicon or silicon dioxide substrates without air gaps.
The study used the Finite Integration Technique (FIT) to numerically simulate the antenna’s performance and evaluated it through S-parameters (such as S11), axial ratio (AR), and gain.
b) Key Research Findings
1. Performance Improvements of the Patch Array Antenna
By introducing cross-shaped slits and crescent-shaped cuts, the impedance bandwidth of the antenna significantly increased. The improved antenna showed excellent performance in the 3.03–3.4 THz and 4.35–5.65 THz bands, increasing bandwidth by 90 GHz and 190 GHz respectively compared to the simple array model. Additionally, the antenna achieved circular polarization characteristics in three bands: 3.2–3.56 THz, 4.48–4.6 THz, and 5.25–5.72 THz.
2. Performance Enhancement from the Bi-layered Metasurface
When the bi-layered metasurface was applied to the improved patch array antenna, the overall performance of the antenna further improved: - The impedance bandwidth extended from 3.24 THz to 5.44 THz, covering a range of 50.7%. - The axial ratio bandwidth exhibited good circular polarization characteristics in four bands (3.48–3.74 THz, 4.08–4.16 THz, 4.23–4.27 THz, and 5.05–6 THz), with a total coverage of 17.2%. - The maximum gain reached 12 dBi, with a maximum aperture efficiency of 77% at 4.32 THz.
3. Comparative Analysis
The study compared the improved antenna with similar structures from existing literature. The results showed that this design outperformed others in terms of bandwidth, axial ratio characteristics, and gain. For example, compared to the antenna proposed by Mabrouk et al. (2023), this design increased the impedance bandwidth by 39% and the axial ratio bandwidth by 6.2%.
Conclusion and Research Value
c) Research Conclusions and Significance
This study successfully designed and validated a high-gain, multi-band circularly polarized bi-layered metasurface patch array antenna. The antenna demonstrated excellent impedance matching characteristics in the range of 3.24–5.44 THz and achieved circular polarization characteristics in four bands. The maximum gain reached 12 dBi, making it suitable for various applications, including 6G communications, drug detection, and security systems.
In terms of scientific value, this study demonstrated how to achieve efficient circular polarization conversion by combining patch arrays and metasurface structures, providing new ideas for terahertz antenna design. In terms of application value, the multi-band characteristics and high gain of the antenna make it an ideal candidate for future wireless communication systems.
d) Research Highlights
- Innovative Design: The combination of bi-layered metasurfaces and patch arrays significantly enhanced the antenna’s circular polarization characteristics and bandwidth.
- Multi-band Characteristics: The antenna achieved circular polarization in four bands, enhancing its applicability across different frequency ranges.
- High-performance Metrics: Maximum gain reached 12 dBi, with an axial ratio bandwidth coverage of 17.2%.
- Material Optimization: Silicon and silicon dioxide were used as substrate materials, reducing signal loss and achieving a low-profile design.
e) Other Valuable Information
The study also explored the radiation efficiency and frequency-dependent characteristics of the antenna. Simulation results showed that the peak gain of the antenna at 4.32 THz was 12.26 dBi, with a maximum aperture efficiency of 77%. These results further demonstrate the antenna’s efficient energy conversion capability.
Summary
This paper presents a high-gain multi-band circularly polarized patch array antenna design based on a bi-layered metasurface. Through detailed experimental procedures and numerical simulations, the study demonstrated the excellent performance of the antenna in the terahertz band. Its innovative design concept and outstanding performance metrics provide important references for the development of future wireless communication technologies.