In this paper, a novel design of square patch antenna with a switchable polarization sense. The propose structure is reconfigurable patch antenna with polarization states being switched among linear polarization (LP), left-hand circular polarization (LHCP) and right-hand circular polarizations (RHCP). This antenna structure has four L-shaped slots on the ground plane, and the Circular Polarization (CP) radiation can be achieved by current perturbation due to the switchable slotted ground plane. The Polarization sense of the proposed antenna is altered by the current path that is redirected with switchable p-i-n diodes on the ground slots. Since the slots and diodes are not on the patch, these are placed on ground so the influences of the slots and p-i-n diodes on antenna performance are minimized. The proposed antenna has a simple and compact structure and can radiate a LP, RHCP & LHCP wave without altering the main beam direction. The results show that polarization reconfigurable antenna has good switchable radiation performance at 2.8 GHz, which can be used for wireless communication systems.