A Compact Wideband Quasi-Yagi Antenna for Millimeter-Wave Communication

A millimeter-wave (mm-Wave) quasi-Yagi antenna utilizing a pair of back-to-back U-shaped full-wavelength dipoles and a folded shorted stub-loaded half-wavelength strip resonator is proposed. The high impedance of the U-shaped full-wavelength dipole overcomes the mismatching problem when it is close to the reflector, enabling compact size in the endfire direction. Three reflection zeros can be obtained from the full-wavelength dipole, the half-wavelength strip resonator, and the equivalent inductor and capacitor derived from the folded shorted stub. The three reflection zeros and appropriate impedance make the proposed antenna have wide bandwidth. For demonstration, a prototype of 1 x 4 array is designed with the antenna element planar size (without ground) of 0.57?(0) x 0.18?(0) (?(0) is the wavelength in the free space at center frequency), the 10 dB impedance matching bandwidth of 49.7% (24.2-40.2 GHz), and the average gain of 9.12 dBi. The proposed compact wideband antenna array can be a good candidate for 5G mm-Wave wireless application.