Defected ground structure (DGS)-integrated arc-cornered rectangular microstrip antenna (RMA) has been investigated to achieve broadband along with high co-polarized to cross-polarized radiation (CP–XP) isolation over principal as well as over skew planes without affecting the dominant mode co-polarized (CP) radiation pattern. The present arc-cornered RMA on circular and rectangular dot-type DGS is thoroughly studied and compared with the conventional rectangular microstrip antenna. In the present paper, a crucial emphasis is given to improve CP–XP isolation in all the skew planes and by employing circular dot-type DGS around 20 dB CP–XP isolation is achieved over whole skew planes as well as in the H-plane with the proposed structure with 20% impedance bandwidth. On the contrary, the CP–XP isolation and impedance bandwidth vary in opposite manner in case of the rectangular dot-type DGS. Around 25 and 10 dB CP–XP isolation with 9 and 22% impedance bandwidth have been obtained with thin and thick rectangular dot-type DGS, respectively. The corners of the patch surface are rounded in such a way to reduce spurious radiations from the sharp corners, which are generally attributed for high XP radiation along the diagonal directions.