A Duplexing Quasi-Yagi antenna

A duplexing quasi-Yagi antenna is proposed in this letter. It consists of two half-wavelength dipoles operating at 3.5/5 GHz. Two half-wavelength resonators are utilized to feed the dipoles and form a second-order filtering response at each passband. Two arms of each dipole are printed on two layers of the substrate, and one arm is a 90° bended half-wavelength resonator in fact, while the other is connected to the ground plane. To improve the directivity, two pairs of striplines are utilized as the director, and the ground plane acts as a reflector. The simulated results show that the antenna can operate at two passbands from 3.29 to 3.64 GHz and 4.7 to 5.2 GHz, with a flat gain in each band. An isolation of over 18 dB is achieved between two channels.