Low-Profile Wideband Dual-Polarized Dipole Antenna With Parasitic Strips and Posts

A low profile ±45°-polarized dipole antenna having an extremely wide bandwidth is proposed. Two crossed dipoles consisting of detached radiation arms are utilized as radiators and they are excited by dual simple striplines. Then several trapezoidal strips and four pairs of rectangular strips are utilized to improve the impedance matching over an exceedingly wide frequency band. For further improving the impedance and stabilizing the radiation pattern, four metallic posts are employed and located around the radiators. Another trapezoidal metal is finally added to the feed stripline of −45° polarization to improve the input impedance for −45° polarization. Our antenna has an extremely broad bandwidth of 80.4% (1.68–3.94 GHz) with VSWR < 1.5, isolation > 27 dB, and steady 3 dB beamwidth [half-power beamwidth (HPBW)] of 66° ± 8° in the operating band. The antenna has compact size of 0.32 λ
_L
× 0.32λ
_L
× 0.15 λ
_L
, where λ
_L
represents the wavelength at the lowest frequency of the operating band.