A NEW DEFECTED GROUND STRUCTURE AND ITS APPLICATION FOR MINIATURIZED SWITCHABLE ANTENNA

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. With the utility of the DGS and artificial cells, the size of proximity coupled antenna is reduced significantly. By introducing a PIN diode at the end of feed line, the antenna is switchable in both x- and y-direction linear polarizations. Such miniaturization in antenna size has little negative effect on its cross polarization, with both simulated and experimental results presented for comparison.