In this study firstly an ordinary microstrip patch antenna is designed at 2,45 GHz resonance frequency as the reference. Then the defected ground structure (DGS) is constructed by etching a Complementary Split Ring Resonator with dumbbell (CSRR-D) on the ground plane of the conventional antenna. The effects of the position on the electrical size are investigated by changing the position of CSRR-D on DGS along vertical direction and the results are compared with reference microstrip antenna. In this study, all the designed antennas are fed by microstrip lines integrated with inset impedance matching technique. The amount of inset is adjusted for each antenna under investigation. Numerical analyses show that DGS composed of CSRR-D provides 45.71 electrical size reduction as compared to ordinary microstrip antenna.