Design of compact and low mutual-coupling quasi-Yagi antenna using stepped-width resonator

A compact microstrip-fed quasi-Yagi antenna using stepped-width resonator is investigated. Analysis for the stepped-width dipole is outlined. In comparison to the conventional one using a uniform-width dipole, the proposed antenna shows a 20% size reduction. Furthermore, the proposed antenna has a lower mutual coupling. The proposed antenna achieves a measured 28% fractional bandwidth with a return loss of greater than 10 dB at the center frequency of 3.3 GHz, a front-to-back ratio of better than 13 dB, and an antenna gain varying from 2.4 dBi to 3.5 dBi.