A simple and compact microstrip antenna of circular geometry with circular cut defected patch surface has been proposed for significant suppression of cross-polarized (XP) radiation compared with maximum co-polarized gain without affecting the co-polarized radiation pattern at its dominant mode. This will enhance the polarization purity in the radiation performance of the proposed antenna. About 27–28 dB isolation between co-polarized and XP radiations is achieved with the proposed structure. The present structure is simple and easy to develop commercially. The investigation of the new structure is carried out with a view to eliminate orthogonal resonance, which is generally attributed for high XP radiation from the microstrip patch antenna with conventional circular geometry. Comprehensive study on the resonance and radiation characteristics of the new geometry is presented. The present investigation provides an insightful visualization-based understanding of XP suppression with the present structure.