Compact wideband antenna above a wideband non-uniform artificial magnetic conductor

A compact wideband antenna place above a non-uniform artificial magnetic conductor (AMC) is presented. The antenna is composed of a wideband coplanar waveguide fed antenna, with wideband harmonic suppression characteristic using non-uniform defected ground structure. Besides, a non-uniform wideband 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 degrees 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 6 9 5 unit cells. The overall dimensions of the complete structure are 0.7 9 x 0.6 lambda(2)(0), where lambda(0) is the free-space wavelength at the lowest frequency. It offers a low-profile configuration with a total thickness of lambda(0)/14.3, and it is matched between 2.5 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 with 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.