A low-profile printed slot antenna (PSA) backed by broadband planar artificial magnetic conductor (AMC) is introduced in this study. Firstly, a suggested PSA with the radiating tapered slots excited by coplanar waveguide (CPW) is used to expand the bandwidth in the measured range of 9-11 GHz (S11≤ -10 dB). Then, the suggested planar AMC surface as the ground plane of the antenna is inserted into the PSA to gain improved radiation efficiency. The realized result from the PSA with the 9×9 planar AMC array exhibits -10 dB measured impedance bandwidth from 6.63 to 13.73 GHz (70%). The suggested PSA with AMC compared to the PSA without AMC exhibits a size reduction of 60%, enhanced bandwidth of 50%, and excellent impedance matching with a minimum value of almost -40 dB. The novel AMC unit cell is realized to operate at 10.14 GHz with an AMC bandwidth of 8-12.35 GHz (43.1%) for X-band operation. Besides, by loading a periodic AMC unit cell into PSA, a high gain of more than 11 dBi with uni-directional radiation patterns is achieved.