Abstract: This letter investigates a method to use the DGS to the dual band antenna with high port isolation. This du al band DGS structure consists of two rectangular codirectional split rings resonator and locates between two patches, the pa rameters of the DGS is analyzed. The dimension of each ring controls the corresponding resonant frequency. Measurement and simulated results confirm the improvement of isolation between the antennas at the radiation frequency of 2. 3/4 GHz when the DGS is utilized. The measured isolation of antenna with DGS has obviously improved more than 9dB by this method in two operating bands.