Broadband Circularly Polarized Cross-Dipole Antenna With Multiple Modes

A broadband circularly polarized (CP) cross-dipole antenna with multiple modes is proposed. The antenna is composed of two pairs of crossed strip dipoles as driven elements, four square-slot patches, and four corner-truncated patches as parasitic elements. A pair of vacant-quarter printed rings is used as sequential phase feeding structure to generate a CP mode, which connect to crossed strip dipoles. By using these coupled rotated elements, multiple CP modes can be stimulated to satisfy the need of broadband CP radiation. In addition, four shorted square metal columns are also introduced in the antenna design to generate an additional CP resonance. A verified prototype was fabricated and measured in this paper. The measured results demonstrate the proposed antenna features wideband CP characteristics with a wide impedance bandwidth (IBW) of 95.5% (0.92-2.60 GHz) and a broad axial-ratio bandwidth (ARBW) of 94.4% (0.95-2.65 GHz).