A new Defected Ground Structure (DGS) is firstly proposed in this paper, which has better slow-wave effect than that of cross or dumbbell one. Using the model of transmission line, its equivalent parameters are extracted. With good omni-directional properties, the proposed DGS is then used in the design of a proximity coupled antenna for its miniaturization. The size of the developed antenna is about 68% smaller than that of the conventional one. Further, two artificial cells are added on the feed line to reduce the protrudent stub length from 26.9mm to 18.94 mm.