Annular ring shaped DGS to reduce mutual coupling between two microstrip patches

Ring shaped defected ground structure (DGS) is explored to reduce mutual coupling between two circular microstrip patches. Reduction by about 4 dB has been demonstrated employing simulation and measurements executed in X-band. The defect surrounding a patch also indicates 5-20 dB reduction in its cross-polarized fields. Although some backward radiation, caused by leakage through the defect, is experimentally observed, they always remain at least 15 dB below the co-polar peak level.