Wideband and Low-Profile Monocone Quasi-Yagi Antenna for Endfire Radiation

This letter presents a low-profile and wideband monocone quasi-Yagi antenna to generate endfire radiation beams. The antenna consists of one driven monocone with two slots cut on the loaded top hat, five identical grounded cones serving as a roll of reflectors, and another two parasitic cones beside the driver to suppress the sidelobe level and improve the front-to-back ratio. The profile of the antenna is very low at $0.15\; \lambda _{0}$ of the center frequency. A broad frequency bandwidth from 6.2 to 18 GHz (98%) for VSWR less than 2 is achieved simultaneously. The antenna also exhibits stable nearly endfire radiation beams over the same frequency range. It is observed that measured results agree well with simulated ones.