Dual-band operation of a circularly polarized radiator on a finite artificial magnetic conductor surface

Abstract

This paper proposes a new way of designing a dual-band circularly polarized (CP) antenna by using a single-band CP radiator on a finite artificial magnetic conductor (AMC) surface. The AMC surface consists of a lattice of square metal plates on grounded dielectric substrate while the single-band radiator is a compact crossed dipole, which employs a 90° phase-delay line consisting of a vacant-quarter printed ring to generate broadband CP radiation. The dual-band operation is obtained by utilizing the original band generated by the radiator and the first additional band caused by surface waves propagating on the finite AMC surface. For verifying the design method, the proposed antenna is optimized for the L1 and L2 bands of the global positioning system with low-profile broadband characteristics and excellent CP radiation. The final design with an overall size of 85 × 85 × 11.493 mm³ (~0.3485λ_o × 0.3485λ_o × 0.0471λ_o at the 1.23 GHz) yields a measured impedance bandwidth of 1.202–1.706 GHz for the |S₁₁| < –10 dB and 3-dB axial ratio bandwidths of 1.205–1.240 GHz and 1.530–1.625 GHz, respectively. Furthermore, the antenna yields right-hand circular polarization and high radiation efficiencies in both bands.

Keywords:

• Circular polarization
• crossed dipole
• artificial magnetic conductor
• surface wave resonance

Acknowledgments

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. 2009-0083512).