A Low-Profile, Directional, Ultrawideband Antenna

A compact, low-profile, ultrawideband (UWB) antenna providing directional radiation pattern is proposed. The antenna is based on a modified Vivaldi antenna and is characterized by a three-dimensionally bended structure. Each of the two radiation fins is capacitively loaded with an invert trapezoidal metallic plate at the end. In order to conveniently mount the antenna on the metal surface, a corrugated plate is added as a ground. Owing to the bended structure and capacitively loaded scheme, the antenna has a low profile of 0.216λ
_m
, where λ
_m
is the wavelength at the minimum operating frequency. The prototype of the antenna is fabricated and measured. The measured and simulated results show good agreement. The measured results show that the antenna has VSWR <; 2.5 from 0.9 to 10 GHz and measured gain from 3.6 to 8.2 dBi.