This communication presents a shorted trapezoidal substrate integrated waveguide (SIW) antenna with a quasi-hemispherical pattern composed of a 64-element (8 x 8) 2-D planar phased array. The proposed low-profile SIW antenna is analyzed in terms of resonating mode and magnetic current and is simulated. The proposed antenna is composed of a trapezoidal patch and shorting vias. The upper side of the trapezoid is the shorting wall. and the middle of the bottom side provides shorting with a via. The resonance produced by the structure causes the magnetic currents to have three different directions. Hence, the single element has a quasi-hemispherical beam pattern on a large ground. The 64-element (8 x 8) 2-D planar phased array was implemented and measured. Because the constituent elements have a quasi-hemispherical pattern, the phased array antenna has a wide scan g range in all azimuth directions. The measured scanning range with 5 dB gain fluctuation in the phi = 0 degrees plane, phi = 45 degrees plane, and phi = 90 degrees plane are 170 degrees , 143 degrees , and 168 degrees, respectively.