This paper proposes a wideband millimeter-wave (MMW) antenna array based on the printed ridge gap waveguide (PRGW). The element of the array consists of a shorted circular patch and a parasitic shorted half annular patch. To improve the impedance bandwidth, the element is fed by using a coupling slot and the distance between the two shorted radiating structure is optimized. Then a $1\times 4$ linear array is developed to increase the realized gain. The simulation results indicate that a -10-dB impedance bandwidth of 10.3 % (26.5 ~ 29.5 GHz, center frequency at 28.0 GHz) is realized for the array antenna. Besides, within its operating band, the realized gain of this array is above 10.5 dBi and the peak gain reaches 12.6 dBi.