This paper presents how to generate a circular polarization in a new microstrip Zeroth Order Resonance(ZOR) metamaterial antenna. The ZOR antenna initially has a linear polarization from a coaxial fed central patch whose edges are coupled to a rectangular ring mushroom. It is a low-profile structure with the -1st resonance as the Left-Handed(LH) region, the ZOR, and the positive resonance as the Right-Handed(RH) region. This antenna is provided with an inclined slot in the ground to form a circular polarization at the LH region, while keeping the frequency response of the antenna's return loss. So the axial ratio over the LH frequency of interest is given to show the circular polarization together with the return loss and radiation pattern to present the design result as is aimed.