A dual-band patch antenna with a shorting wall and a U-shaped slot is presented in this paper. The shorted-patch is coupled with the aperture slot that is closely placed to the shorting wall for achieving good impedance matching. A U-shaped slot is embedded in the shorted-patch and is located near the radiating edge to yield a dual-band operation. By changing the side slot length of the U-shaped slot, the tunable frequency ratio of the proposed antenna is varied from 1.73 to 2.05.