A Miniaturized Antenna by Loading Curved Branches for UWB Applications

In this paper, a compact Vivaldi antenna with a pair of curved branches is proposed. Compared to the traditional Vivaldi antenna, by adding a pair of curved branches, an additional resonant frequency is added in the low frequency band, and the bandwidth edge of the antenna at the low frequency band extends to 2.45 GHz, and the sidelobe level of the radiation pattern is reduced. In the operating band, the gain of the antenna is also improved a lot. In order to verify the validity of this proposed design, the proposed antenna model was fabricated and measured. The measured results show that this proposed antenna can cover a wide operating bandwidth of 2.45 GHz–11.5 GHz in a compact size of 30 mm × 36 mm and achieve good directional radiation characteristics. In the operating band, the measured gain is higher than 4 dBi. In addition, the measured group delay of this antenna is around 1.6 ns, and its variation is less than ±0.5 ns.