A compact wideband antenna place above a non-uniform Artificial Magnetic Conductor (AMC) is presented. The antenna is composed of a wideband Coplanar Waveguide (CPW) fed antenna, with wideband harmonic suppression characteristic using non-uniform defected ground structure (DGS). Besides, a non-uniform wideband Artificial Magnetic Conductor (AMC) is designed. The AMC unit cell is composed of a square patch into which a four arms spiral shape is etched. It exhibits a wider +/-90° bandwidth than the spiral unit cell and a smaller size than the square patch unit cell. The antenna is placed above the proposed AMC structure formed by 6x5 unit cells. The overall dimensions of the complete structure are 0.7x0.6 λ02, where λ0 is the free-space wavelength at the lowest frequency. It offers a low profile configuration with a total thickness of λ0/14.3 and it is matched between 2.5 GHz and 5.4 GHz (73.5%). Furthermore, it has a stable main lobe radiation pattern in the E and H planes within the operating frequency band. Moreover, compared to the antenna without AMC, the broadside realized gain is significantly increased. A prototype has been realized and there is a good agreement between simulated and measured results. Furthermore, the proposed structure presents a size reduction of about 34 %, and better radiation characteristics in comparison with the conventional square AMC.