Wideband circularly polarized low-profile antenna using artificial magnetic conductor

Abstract

A wideband circularly polarized (CP) antenna with an artificial magnetic conductor (AMC) reflector is presented. Its primary radiation elements are composed of two bowtie dipoles which are arranged orthogonally through double-printed rings to allow easy impedance matching and produce good CP radiation. Planar periodic square metallic plates, which behave as AMC surfaces when placed on a grounded dielectric substrate, are appropriately incorporated with crossed bowtie dipoles to achieve the desired unidirectional radiation, low profile, as well as wideband features. The final design with an overall size of 0.75λ_o × 0.75λ_o × 0.11λ_o (λ_o is the free space wavelength at 5 GHz) resulted in a measured –10 dB |S₁₁| bandwidth of 54.2% (4.3–7.5 GHz) and a 3-dB axial ratio bandwidth of 33.3% (5–7 GHz). The antenna yields right-hand circular polarization and broadside gain of approximately 7.9 dBic across the CP operating bandwidth.

Keywords:

• Circular polarization
• broadband
• bowtie antennas
• crossed dipole
• artificial magnetic conductor