Directivity Enhancement of Planar Endfire Circularly Polarized Antenna Using V-shaped 1.5-Wavelength Dipoles

A novel planar endfire circularly polarized antenna with simple configuration and enhanced directivity is proposed. Two V-shaped dipoles operating at resonant 1.5-wavelength dipole mode are arranged to form a planar Yagi structure. In this way, both the azimuthal and elevational principal-cut planes could be effectively narrowed down. This leads to a directivity enhancement up to 4 dB in the endfire direction. As experimentally validated, the proposed antenna with a very low profile of 0.034 wavelength can exhibit measured gain of 6.1 dBic in the endfire direction.