Abstract: A Ku-band antenna array with fixed beam in elevation and frequency-scanning beam in azimuth was designed and implemented. By introduced double-layer microstrip patch configuration, element of the column linear array with 18% bandwidth was designed. In order to realize the beam scanning with frequency changed in azimuth and improve the array efficiency, the waveguide slow-wave line structure with electromagnetic coupled slot on narrow side was used as feed line. Based on the successful simulation results achieved by HFSS software, antenna array with 12×40 elements was implemented and tested. The results show that, except at the center frequency, the voltage standing wave ratio(VSWR) of the antenna array is below 1.5 at the operation band, the scan scope is up to 80 degree, the sidelobe is below -20 dB, and the gain is more than 26.5 dB.