A novel compact defected ground structure and its application in mutual coupling reduction of a microstrip antenna
In this paper, a novel compact T shape defected ground structure (DGS) is proposed in order to reduce the mutual coupling between elements in a microstrip antenna array structure. The proposed DGS has considerable advantages compared to an H shaped DGS. As is known, DGS insertion is a common problem in microstrip antenna array structures. However, the proposed T shaped structure is more compact so it could be suitable for a compact microstrip array antenna. The T shaped DGS is about 24% more compact than the H shaped one. However, the most important novelty of our work is reducing mutual coupling both in the E plane and the H plane, which previously was discussed just in the E plane. Finally, we have considered the disturbing effect of mutual coupling on the side lobe level (SLL) of unequally spaced arrays; using these results, a T shaped DGS has been implemented in an 8 element unequally spaced array antenna in order to reduce its SLL.