An Ultra-Wideband Antenna with Unidirectional Radiation Characteristics

An ultra-wideband antenna operating from 1 to 4 GHz with unidirectional radiation patterns has been proposed in this paper. The antenna consists of a pair of L-shaped patches, a parallel tapered balun, a parasitic ring and a ground plane. The wideband performance is obtained by exciting the antenna with a tapered balun. In addition, the impedance bandwidth is further enhanced by introducing the parasitic ring which is supported by four Nylon posts. The obtained results can confirm that the proposed antenna has achieved a wide impedance bandwidth (VSWR ≤ 2) of about 120%, stable radiation patterns, consistent gain response of over 6.5dBi and low cross-polarization levels over the whole operating frequency band.