A broadband planar quasi-Yagi antenna with X-shaped driven elements

In this paper, a novel wideband planar quasi-Yagi antenna with x-shaped elements is presented. Good impedance matching and mode transforming are realized by using an exponentialy tapered microstrip balun. This quasi-Yagi antenna is designed on FR-4 substrate whose dielectric constant is 4.4 and the thickness is 1.6 mm. Prototype antennas have been fabricated and measured. Experimental results show that the 10 dB return loss bandwidth of this antenna is 48% operating from 4.7 GHz to 7.6 GHz and the gain is higher than 6.2 dB.