Two-dimensional fractal metasurface and its application to low profile circularly polarized antennas

Abstract

Two-dimensional (2D) Wunderlich-shaped fractal reactive impedance surface (WRIS) is designed and extensively investigated to reduce the dielectric substrate thickness without deteriorating the electromagnetic characteristic. Slot resonators, Hilbert-shaped complementary single ring resonator (HCSRR), and the complementary three-turns spiral resonator have been used to achieve antenna miniaturization and also to render the circularly polarized (CP) wave. For demonstration, WRIS-inspired HCSRR- and TCSR-loaded CP antennas are optimized, fabricated, and measured. Numerical and experimental results indicate that both antennas owe compact size smaller than 0.18λ₀ × 0.25λ₀ ×  0.017λ₀, exhibit comparable impedance, and axial ratio (AR) bandwidth better than 1.60% and pure CP performances. Furthermore, the antennas are free of metallic via holes and easy of fabrication, indicating promising applications in wireless communication systems.

Keywords:

• Wunderlich-shaped fractal reactive impedance surface
• Hirbert-shaped complementary single ring resonator (HCSRR)
• the complementary three-turns spiral resonator (CTSR)
• miniaturization
• compact
• circularly polarized antenna

Acknowledgements

The authors would like to thank the China North Electronic Engineering Research Institute for the fabrication.

Additional information

Funding

This work is supported by the National Natural Science Foundation of China under [grant number 61372034].